Hybrid zygotes sometimes develop into adults, such as mules (hybrids between female horses and male donkeys), but the adults fail to develop functional gametes and are sterile. This phenomenon is called as hybrid sterility. Thus, option B is correct. 

Embryo cryopreservation or preservation of embryo is generally performed as a component of in vitro fertilization which generally also include ovarian stimulation, ovarian hyperstimulation or superovulation, egg retrieval, artifical insemination and embryo transfer.

Artificial insemination is a globally accepted method of breeding cattle and is also effective for other species. Semen can be stored deep-frozen in liquid nitrogen, in a chilled liquid form or at room temperature. Its low temperature of $-196^0$C and inert caracteristics prevent the deterioration of biological quality. Hence, option C is correct.

The Bt brinjal is a suite of transgenic brinjals created by inserting a crystal protein gene (Cry1Ac) from the soil bacterium Bacillus thuringiensis into the genome of various brinjal cultivars. The insertion of the gene, along with other genetic elements, such as promoters, terminators and an antibiotic resistance marker gene into the brinjal plant is accomplished using Agrobacterium-mediated genetic transformation. 

(d) Gossypium arboreum, G. herbaceous - old world
species - 2n = 26 Diploid Gossypium hirsutum, G.
barbedens- new world species - 2n = 52 tetraploid.

Triticum monococcum is a diploid wheat variety with 14 (2n) chromosomes. It is also called Einkorn wheat and it is the most ancient species of wheat.

The tomato variety 'Flavr Savr' presents an example where expression of a native tomato gene has been blocked. Fruit softening is promoted by the enzyme polygalacturonase, which degrades pectin. Production of polygalacturonase is blocked in the transgenic tomato variety 'Flavr Savr'. So, fruits of this tomato variety remain fresh and retain their flavour much longer than do the fruits of normal tomato varieties. Additionally, the fruits have a superior taste and increased total soluble solids.

GM food or genetically modified food is obtained from crops improved by artificial mutagenesis and non-natural crosses between unrelated species. GM food production does not involve use of pesticides etc., but includes incorporation of pest resistance genes either through mutation or through transferring it from an insect resistant species.

Genetically modified crops (GMCs, GM crops or biotech crops) are plants used in agriculture, the DNA of which has been modified using genetic engineering techniques. In most cases the aim is to introduce a new trait to the plant, which does not occur naturally in the species. 

Genetically modified foods or GM foods, also genetically engineered foods, are foods produced from organisms that have had changes introduced into their DNA using the methods of genetic engineering.

McCain foods has decided to stop processing genetically modified potatoes, because of pressure from consumers who fear damage to the environment and human health. 

In conditions of high salinity, an important mechanism to survive salt stress relies on the accumulation of excess cytoplasmic Na+ in vacuoles, reducing the amount in the cytoplasm and providing osmotic pressure. The transgenic plants accumulate more Na and K in their leaf tissue. The increased accumulation of sodium is due to the consequence of the activity of the vacuolar sodium proton antiporter. The net increase in the concentration of solutes in the cell leads to an increase in the uptake of water so that the transgenic plants can maintain turgor. 

A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. Genetic modification involves the mutation, insertion, or deletion of genes. Inserted genes usually come from a different species in a form of horizontal gene-transfer. Hence, the genetic material need not be inserted again in each generation.

Alcoholic fermentation occurs in the production of alcoholic beverages and ethanol fuel, and in the rising of bread dough. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process.

Fermentation is a metabolic process that converts sugar to acids, gases and/or alcohol. It occurs in yeast and bacteria. Fermentation has been used by humans for the production of food and beverages as well as for producing alcoholic beverages such as wine and beer.

The selected strains of Saccharomyces cerevisiae, used in baking industry to bring about desired changes in flavour and texture of the baked products, are sold as baker's yeast. These yeasts have ability to ferment the sugar in the dough. The carbon dioxide produced during fermentation is responsible for the leavening (i,e., raising of the dough). Both CO$ _2$ and alcohol escape during baking so that the bread and other baked products become porous and soft.

Yeasts are the main producers of wine and beer. In that the most important and high yielding strain is the saccharomyces cerevisiae. They ferment the sugars that comes the grapes and barley. 

Murray and Peterson demonstrated the utility of fungi for steroid conversion by using the Rhizopus stolonifer. Whereas the technique for development of monoclonal antibody was demonstrated by Kohler and Milstein. Waksman and Monad demonstrate the synthesis of streptomycin antibody from streptomyces species. Kornberg and Miller are known for the purification of the DNA polymerase 1 enzyme. Thus, the correct answer is option B.

Aspergillus is utilized industrially in a number of ways. Most sodas and soft drinks contain citric acid as the main ingredient. Citric acid is also used in other drinks, many candies, canned goods, baked goods, etc. It is too expensive to isolate the citric acid from citrus fruits so it is produced in the large-scale fermentation of sugar by utilizing Aspergillus niger. 

Cider is also called the apple cider. This is an alcoholic product that is prepared from the fermentation of apples with the yeast Saccharomyces. Whereas Lactobacillus in milk converts it into the curd, Saccharomyces produces alcohol by the fermentation process in cane sugar and Bacillus Is used to bleach ramie fiber. Thus, the correct answer is option B.

The term "Yeast" is a morphological term that refers to a one-celled fungus. Most yeasts, including Saccharomyces reproduce by budding, where the daughter cells bleb off from a small pore in the side of the mother cell. S. cerevisiae is famously known for its role in food production. It is the critical component in the fermentation process that converts sugar into alcohol, an ingredient shared in beer, wine and distilled beverages. It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. Because of its role in fermentation, humans have known about and used Saccharomyces cerevisiae for a long time. In a process called as fermentation, yeast feeds off sugars from their substrate and convert it to ethanol, giving these beverages their alcoholic content. Depending on the beverage, yeast is incorporated into the creation process in several ways.

Ethanol fermentation is a biological process to produce ethanol and carbon dioxide as metabolic waste products. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process. 

Saccharomyces cerevisiae (Common name is Baker's or brewer's yeast) is a species of yeast generally used in the production of ethyl alcohol in beer and wine making process. In the production of ethyl alcohol, the fungus Saccharomyces produces the enzyme zymase. This zymase will then acts on Glucose to produce ethyl alcohol. Thus, the correct answer is option A.

Dairy products have generally been considered an excellent source of high-quality protein, calcium, potassium, phosphorus, magnesium, zinc, and the B vitamins riboflavin, niacin, vitamin B-6, and vitamin B-12. The final nutritional composition of yogurt is affected by the species and strains of bacteria used in the fermentation, the source and type of milk solids that may be added before fermentation, and the temperature and duration of the fermentation process.

Traditional animal rennet is an enzyme derived from the stomachs of calves, lambs or goats. Rennet is used in the production of most cheeses. Chymosin, its key component, is a protease enzyme that curdles the casein in milk. 

Acetobacter suboxydans is a gram-negative bacteria of the order rhodospirilla. It is used in the formation of ascorbic acid. A. suboxydans is widely used commercially in the production of ketonic acids like ascorbic acid (Vitamin C). 

Sourdough (leavened bread) is a bread product made by a long fermentation of dough using naturally occurring Lactobacilli and yeasts. The most commonly used yeast species in the production of sourdough are Kazanchastania exigua (Saccharomyces exiguous), Saccharomyces cerevisiae, Candida Milleri, and Candida humilis

Malted barley is barley that has been allowed to germinate (sprout) to a degree and is then dried. The germination process converts starch, the seed's stored energy, into simpler sugars used in its initial growing stage. The conversion of starch to sugar is accomplished by diastase enzymes that the seed produces during this process. The germination and drying stages capture fermentable sugars, soluble starch, and the diastase enzymes for beer brewing. 

Lactic acid fermentation is a biological process by which glucose and other six-carbon sugars are converted into cellular energy and the metabolite lactate. Lactic acid fermentation is caused by some fungi and bacteria. The most important lactic acid producing bacteria is Lactobacillus. The presence of lactic acid, produced during the lactic acid fermentation is responsible for the sour taste and for the improved microbiological stability and safety of the food. This lactic acid fermentation is responsible for the sour taste of dairy products such as cheese, yoghurt 

Rennet is a complex of enzymes produced in stomachs of ruminant mammals which is used in the production of most cheeses. Chymosin, its key component, is a protease enzyme that curdles the casein in milk, helping young mammals digest their mothers' milk. It can also be used to separate milk into solid curds used for cheesemaking and liquid whey.

There are four principal methods available for immobilizing enzymes as follows:

Fermentation is an anaerobic process in which energy can be released from glucose even though oxygen is not available. Fermentation occurs in yeast cells. Yeasts are able to participate in fermentation because they have the necessary enzyme to convert pyruvic acid to ethyl alcohol. 

Large-scale, commercial production of citric acid is done by the microorganism, Aspergillus niger by aerobic fermentation of sucrose in beet molasses, a mould belonging to the same family as the penicillins.

Chlorellin, contained in chlorella, acts like a natural antibiotic. In contrast to chemical antibiotics, it combats pathogenic bacteria without altering the intestinal flora.

The most well known examples of yeast fermentation are in the production of alcoholic drinks and the leavening of bread. For their participation in these two processes, yeasts are of major importance in the food industry. Varieties of the Saccharomyces cervisiae genus are the most common yeasts in fermented foods and beverages. 

Streptomycin is an antibiotic that inhibits both gram-positive and gram-negative bacteria and is therefore a useful broad-spectrum antibiotic.

Brewer's yeast is often used as a source of B-complex vitamins, chromium, and selenium. The B-complex vitamins in brewer's yeast include B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B9 (folic acid), and H or B7 (biotin). These vitamins help break down carbohydrates, fats and proteins, which provide the body with energy. They also support the nervous system, help maintain the muscles used for digestion, and keep skin, hair, eyes, mouth, and liver healthy.

Rennin, also called as chymosin, protein-digesting enzyme that curdles milk by transforming caseinogen into insoluble casein; it is found only in the fourth stomach of cud-chewing animals, such as cows. Its action extends the period in which milk is retained in the stomach of the young animal. In animals that lack rennin, milk is coagulated by the action of pepsin, as is the case in humans. A commercial form of rennin, rennet, is used in manufacturing cheese and preparing junket.

Secondary metabolites, including antibiotics, are produced in nature and serve survival functions for the organisms producing them. Secondary metabolites serve: (i) as competitive weapons used against other bacteria, fungi, amoebae, plants, insects, and large animals; (ii) as metal transporting agents; (iii) as agents of symbiosis between microbes and plants, nematodes, insects, and higher animals; (iv) as sexual hormones; and (v) as differentiation effectors. Although antibiotics are not obligatory for sporulation, some secondary metabolites (including antibiotics) stimulate spore formation and inhibit or stimulate germination.

S. cerevisiae is known for its role in food production. It is the critical component in the fermentation process that converts sugar into alcohol, an ingredient shared in beer, wine, and distilled beverages. It is also used in the baking process as a leavening agent.

Zymase, an enzyme from yeast, changes the simple sugars into ethanol and carbon dioxide.

Penicillin is one of the first and still one of the most widely used antibiotic agents, derived from the Penicillium mold.

Yoghurt is produced through the fermentation of milk by lactic acid bacteria, usually Lactobacillus bulgarius and Streptococcus thermophilus. Acetobacter aceti bacteria are a widespread group of gram-negative, obligate aerobic rods which oxidize ethanol (alcohol) into ethanoic (acetic) acid.

Alcohol fermentation is done by yeast and some kinds of bacteria. These microorganisms convert sugars into ethyl alcohol and carbon dioxide.

Ergot or ergot fungi refers to a group of fungi of the genus Claviceps. The most prominent member of this group is Claviceps purpurea ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that can cause ergotism in humans and other mammals who consume grains contaminated with its fruiting structure.

Penicillium roqueforti is a common saprotrophic fungus. The major industrial use of this fungus is the production of blue cheese, flavouring agents, antifungals, polysaccharides, proteases and other enzymes. The fungus has been a constituent of roquefort, stilton, Danish blue, cabrales and other blue cheese.

There are several types of cheese, which are grouped or classified according to criteria such as length of ageing, texture, methods of making, fat content, animal milk, country or region of origin, etc. The method most commonly and traditionally used is based on moisture content, which is then further narrowed down by fat content and curing or ripening methods.

Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae.

Penicillin is produced by strains of the fungus Penicillium notatum and P. chrysogenum. Most of the other antibiotics in clinical use are produced by actinomycetes, particularly streptomycetes (natural antibiotics). 

Serratia is a genus of gram negative, facultatively anaerobic, rod-shaped bacteria of the enterobacteriaceae family. The most common species S. marcescens, is normally the only pathogen and usually causes nosocomial infections.

Sugarcane (Saccharum or Hidnarum) is the main source of commercial ethyl alcohol. Source is extracted from the juice of sugarcane as a commercial product, but this leaves a syrup called molasses which contains glucose and fructose. Ethanol is produced by the fermentation of molasses by using yeast Saccharomyces cerevisiae.

Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. During the bread making fermentation process, yeast gives off carbon dioxide and produces enzymes that modify the physical properties of the dough. 

Fermenting agents are Saccharomyces cerevisiae, S.sake, S.ellipsoidens. Molasses and fruit juice are more commonly used in brewing industry. Molasses is a dark coloured syrup left after the extraction of sugar. Yeasts are used as supplement to human food, Brewer's yeast is a readily available source of protein. At present the scientists are thinking of microscopic forms of food  (fungi as a single cell protein) or atleast as food flavouring agent

Single-cell protein refers to sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds.

In stirred tank bioreactors, the oxygen mass transfer is a function of many variables, such as the physical properties of the liquid (viscosity, surface tension, etc.), the geometry of the vessel and stirrer and the operational conditions. In the stirred-tank bioreactor, the stirrer facilitates even mixing and oxygen availability throughout the bioreactor. 

Red yeast is used for maintaining desirable cholesterol levels in healthy people. The active ingredient in red yeast is the same as the active ingredient in prescription drugs called statins used for high cholesterol. Thats why, red yeast has all the possible side effects, drug interactions, and precautions associated with this type of drug.

The bacterium Clostridium acetylbutylicum, easliy converts any fermentable sugar to butanol and additionally produces hydrogen gas, acetone, isopropyl alcohol. Isopropanol is a product of the organism formerly known as Clostridium butylicum, which is now included in the species Clostridium beijerinckii. 

Molasses are used commonly in distilleries for ethanol production. Saccharomyces cerevisiae is an industrial yeast possessing most of the desirable fermentation characteristics like fast growth and fermentation rate, osmo-tolerance, high ethanol tolerance, ability to ferment molasses, and to ferment at elevated temperatures etc.

Raw fruit juice is usually a strongly acidic solution, containing from 10 to 25 percent soluble sugars. Its acidity and high sugar concentration make it an unfavourable medium for the growth of bacteria but highly suitable for yeasts and moulds. Raw fruit juice naturally contains many yeasts, moulds, and bacteria, derived from the surface of the fruit. Normally, the yeast used in alcoholic fermentation is a strain of the species Saccharomyces cerevisiae

When yeast is added to a mixture of dough, a fermentation process begins as the yeast eats the sugars and releases carbon dioxide gas. The yeast absorbs the oxygen in the dough as it begins a reproduction of cells, dividing the single yeast cell into two cells, which then become four, and redividing continuously into increasingly larger numbers of cells. Trapped in the dough, the yeast cells produce carbon dioxide resulting in the rising of the dough until it reaches a point in size to be burst, reducing it back into its original shape to begin the rising process again. This second rising is faster due to the abundance of cells now present from multiplying continuously.

• Single-cell proteins refer to edible unicellular microorganisms. 
• The biomass or protein extract from pure or mixed cultures of algae, yeasts, fungi or bacteria may be used as an ingredient or a substitute for protein-rich foods and is suitable for human consumption or as animal feeds. 
• Hence, The method of producing proteins for food or feed-through microbial biomass is called as SCP (Single Cell Protein).
• So, the correct answer is 'SCP (Single Cell Protein)'.

Single-cell protein (SCP) refers to sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds. Single-cell proteins develop when microbes ferment waste materials including wood, straw, cannery and food-processing wastes, residues from alcohol production, hydrocarbons, or human and animal excreta.

It has been demonstrated that Propionibacteria species has the highest potential to accumulate vitamin B$ _{12}$ intracellularly. Propionibacterium shermanii and Propionibacterium freudenreichii are most widely used. Propionibacteria produce vitamin B$ _{12}$ intracellularly and excrete mainly propionic acid and acetic acid extracellularly. All Propionibacterium strains employed for vitamin B$ _{12}$ production are microaerophilic and produce vitamin B$ _{12}$ in high yields only under very low oxygen concentrations.

Plants and animals do not have the capacity to synthesize vitamin B12 by their own. But the microorganisms like Saccharomyces cerevisiae ( contains vitamin B12 but there is no clear answer about the source of synthesizing vitamin B12 in this yeast. But it synthesizes vitamin B12.), acetobacter and also by the mushrooms Agaricus. Thus, the correct answer is option D.

The curdling step in cheese making relies on lactic acid bacteria. These bacteria are able to ferment the carbohydrates found in the milk, releasing lactic acid in the process. The lactic acid causes the proteins dissolved in the milk to precipitate, or come out of solution. When the proteins precipitate, they pull out the fats as well. What you are left with is similar to the sour milk from the introduction: the liquid whey filled with many solid chunks of protein and fat, called curds.

The overall process of fermentation is to convert glucose sugar (C$ _6$H$ _{12}$O$ _6$) to alcohol (CH$ _3$CH$ _2$OH) and carbon dioxide gas (CO$ _2$). The reactions within the yeast to make this happen are very complex but the overall process is as follows: 

Chymosin, known also as rennin, is a proteolytic enzyme synthesized by chief cells in the stomach in young ruminants. Its role in digestion is to curdle or coagulate milk in the stomach, in the very young animal. Chymosin efficiently converts liquid milk to a semisolid like cottage cheese, allowing it to be retained for longer periods in the stomach. It is widely used in the production of cheese. 

Beer is an alcoholic beverage produced by the saccharification of starch and fermentation of the resulting sugar. The starch and saccharification enzymes are often derived from malted cereal grains, most commonly malted barley and malted wheat.

Lactobacillus bacteria have the ability to convert sugars into lactic acid. The Lactobacillus strain is so named because it was first studied in milk ferments. These bacteria readily use lactose or other sugars and convert them quickly and easily to lactic acid.

Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus. Various strains of A. niger are used in the industrial preparation of citric acid and gluconic acid.

S. cerevisiae is known for its role in food production. It is the critical component in the fermentation process that converts sugar into ethyl alcohol (ethanol), an ingredient shared in beer, wine and distilled beverages. It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. 

S. cerevisiae is known for its role in food production. It is the critical component in the fermentation process that converts sugar into ethyl alcohol (ethanol), an ingredient shared in beer, wine and distilled beverages. It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. 

In a bread dough, where the oxygen supply is limited, the yeast can only partially breakdown the sugar. Alcohol and carbon dioxide are produced in this process known as alcoholic fermentation. The carbon dioxide produced in these reactions causes the dough to rise, and the alcohol produced mostly evaporates from the dough during the baking process. During fermentation, each yeast cell forms a centre around which carbon dioxide bubbles form. Thousands of tiny bubbles, each surrounded by a thin film of gluten form cells inside the dough piece. The increase in dough size occurs as these cells fill with gas.

Yogurt is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as yogurt cultures. Fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and its characteristic tang. Some representative strains of yogurt cultures are Streptococcus lactis, S. cremoris, S. thermophilus, Lactobacillus bulgaricus, L. acidophilus, and L. plantarum.

Vitamin B$ _{12}$ cannot be made by plants or animals as only bacteria have the enzymes required for its synthesis. Members of the genus Propionibacterium are widely used in the production of vitamin B$ _{12}$.

Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, which is the same species (but a different strain) commonly used in alcoholic fermentation, which is called as brewer's yeast.

Microorganisms isolated based on their ability to degrade hydrocarbons often belong to the genus Pseudosmonas. These bacteria have several catabolic pathways and are easily handled and grown in the laboratory. Pseudomonas putida, a Gram-negative proteobacterium, possesses the outstanding ability to tolerate high concentrations of different hydrocarbons.

Useful antibiotics are often discovered using a screening process. To conduct such a screen, isolates of many different microorganisms are cultered and then tested for production of products that inhibit the growth of test organisms.They are tested for their selective toxicities and therapeutic activities, and the best candidates are examined and modified. Once the process is complete, the antibiotic must be extracted and purified to a crystalline product. The copies of genes coding for enzymes involved in the antibiotic production can be inserted into a cell, via vectors such as plasmids.

Scientic theories about the origin-of-life theories have historically been characterized by the chicken-and-egg problem of which essential aspect of life was the rst to appear, replication or self-sustenance. RNA, the other nucleic acid, contained building blocks very similar to DNA, so biologists recognized early that RNA could store information in its linear sequences. With the discovery in the 1980s that RNA molecules were capable of biological catalysis, a function till now ascribed to proteins alone, RNA took on the role of the single entity that could act as both chicken and egg. Within a few years of the discovery of these catalytic RNAs (ribozymes) scientists had formulated an RNA hypothesis that posited an early phase in the evolution of life where all key functions were performed by RNA molecules. 

Beverages of low alcoholic content (less than about 9% alcohol) are fermented from grains and are usually considered to be beers. Wines, on the other hand, are fermented to a higher percentage of alcohol (10 - 18% alcohol) and are usually fermented from fruit juice. Higher levels of alcohol kill or inhibit bacteria stopping spoilage as well as fermentation. Vodka, whiskey, and other alcoholic beverages with alcohol contents well above 20% are produced by distilling alcohol from a yeast-fermented beverage. Many liquors are produced by using distilled alcohol (as high as 95% alcohol) to extract various flavoring materials after which the resulting extract is diluted with water and often sugar to make a flavored alcoholic beverages. Unless the alcoholic content of the resulting beverage is well above 15%, the material will not be stable and may start to ferment or even decay in storage. Hence, most liquors are atleast 20% alcohol.

Biotechnology has a long history of use in food production and processing. For ten thousand years fermentation, a form of biotechnology, has been used to produce wine, beer and bread. Selective breeding of essential foods such as rice, corn and wheat have created thousands of local varieties with improved yield compared to their wild ancestors.

G.M. Findley and McCallum (1937) reported a phenomenon, called viral interference in which the cell infected with one type of virus becomes reisstant to superinfection by other viruses. Alliac Issacs and Lindeman (1957) gave the term interferons to the chemical substances responsible for the viral inference. 

Genetic engineering is the branch of science which deals with the modification of genes. The desired genes is isolated from the host and are inserted into the vectors. The vectors carries the foreign gene into the desired organism and multiples. The foreign gene multiplies along with the vector and produce a new character.

Barley contains the largest amount of enzymes necessary for converting starches to ferment sugars. Barley is commonly used in breads, soups, stews though it is primarily grown as animal fodder and as a source of malt for alcoholic beverages, especially beer.
Thus, the correct answer is option (D), 'Barley'.

Escherichia coli are Gram-negative, facultative aerobic bacteria. They are common inhabitant of human gut. These strains of E. coli are harmless. They form the part of the normal microbiota of the intestine. They live in symbiotic association. They benefit hosts by producing vitamin K$ _2$ and preventing colonization of the intestine with pathogenic bacteria.

Riboflavin (vitamin B$ _{2}$) is part of the vitamin B group. It is the central component of the cofactors FAD and FMN and as such required for a variety of flavoprotein enzyme reactions including activation of other vitamins. Various biotechnological processes have been developed for industrial scale riboflavin biosynthesis using different microorganisms, including filamentous fungi such as Ashbya gossypii, Candida famata and Candida flaveri, as well as the bacteria Corynebacterium ammoniagenes and Bacillus subtilis. Strains of yeast of the species Candida famata also used to synthesis ribiflavin. Thus, option C is correct. Microorganism Acetobacter is used to yield ascorbic acid. Thus, option D is wrong. Yeast does not yields tocopherol and vitamin B$ _{12}$. Thus, option A and B are wrong.