• Transfer of pollen grains from the male reproductive organ (anther) of one plant to the female reproductive organ (stigma) of another plant. 
• Insects and wind are the main agents of cross-pollination.
  
• Thus, it creates genetic variations in the plants making it more resistant to diseases and other conditions than the parent plants.

Allogamy is also called as cross pollination. In the case of allogamy, the pollen from a flower falls on the flower of a different plant. This causes the genetic recombinations to take place. This is not possible in any other type of pollinations. Thus it produces the superior progeny.

Emasculation involves the removal of stamens from bisexual flowers of the female parents in order to avoid self-pollination in these flowers. It is done before the anthers mature. If in a condition the female parent bears bisexual flowers, then elimination of anthers from the flower bud before the anther dehisces by means of a pair of forceps is necessary. This step is called as emasculation.

Cross-pollination is advantageous because it results in formation of better progeny. The transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and wind are agents of cross-pollination.

• Emasculation is the removal of anthers in a bisexual flower to prevent self-pollination. 
• The female reproductive part is not involved in this process. It is a technique used by plant breeders to obtain the desired variety by crossing a plant with the desired pollen grain obtained by emasculation. 

Cross-pollination is the transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and the wind are the main agents of cross-pollination. 

Cross pollination: The transfer of pollen from the anthers of one flower to the stigma of another flower by the action of wind, insects, etc. It requires production of large number of pollen grains. Progeny shows enhanced vigor.
Offsprings are more viable and resistant. There is a possibility to get new desirable characters. Yield of crop can be maintained. It helps in evolution.
Undesirable characters of the plant can be eliminated.

Emasculation involves the removal of anthers of a flower in order to prevent self-pollination or the undesirable pollination of neighbouring plants. After emasculation the female reproductive part of the plant should be covered to prevent unwanted fertilisation.
Thus, the correct answer is option (B), 'Removal of anthers'.

• Emasculation is the removal of anthers in a bisexual flower to prevent self-pollination. 
• The female reproductive part is not involved in this process. It is a technique used by plant breeders to obtain the desired variety by crossing a plant with the desired pollen grain obtained by emasculation. 

Cross pollination occur when pollen grains are transferred to a flower from a different plant. The plants that undergo cross pollination often have taller stamens than their carpels. They use mechanisms to ensure that the pollen grains are spread to other plants' flowers. The process of cross pollination requires the help of abiotic or biotic agents like wind, water, insects, birds, bats, snails and other animals as pollinators. 

Herkogamy - common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male and female function. Herkogamy differs from other such strategies by supplying a spatial separation of the anthers and stigma.
Dichogamy - having pistils and stamens that mature at different times, thus promoting cross - pollination rather than self - pollination.
Self sterility - sterile to its own pollen or sperm.

Pollination is a process in which pollen is transferred to the female reproductive organs of seed plants, thereby enabling fertilization and reproduction through growth of the pollen tube and eventual release of sperm. Both gymnosperms and angiosperms undergo pollination, although the mechanism for angiosperms is much faster and more complex. A successful angiosperm pollen grain (gametophyte) containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. Pteridophytes and bryophytes pollination does not occur. 

Cleistogmay is also called as automatic self - pollination. It describes the trait of certain plants to propagate using non - opening, self - pollinating flowers.

Mass selection is a simplest , common and oldest method of crop improvement, in which large number of plants of similar phenotype are selected and their seeds are harvested and mixed together to constitute the new variety. This method is practised in both self and cross – pollinated crops and plants are selected on the basis of their phenotype of appearance. Therefore, selection is done for easily observable characteristics such as plant height, ear/type, grain colour, grain size, etc.

• Cross-pollination is important for the production of new varieties of plants. Plants are having better growth and the creation of more viable seeds.  
• Cross-pollination is the process where the plants of different variety can breed with another to create a unique plant. 
• The resultant plant shows the characteristics of both the parent generation and therefore it is used to create new varieties of plants. 
• Cross-pollination is also performed to create more viable seeds of plants and also to generate plants having a better scope of growth.
• The correct option is D. 

If it produces a pink flower in the next generation then cross-pollination might have occurred.

Incomplete dominance or blending dominance is a type of inheritance where the hybrid is not related to either of the parents but exhibit a blending of characters of the two parents.

• Cross-pollination is the transfer of pollen from the anthers of one flower to the stigma of another flower by the action of wind, insects, etc. 
• The two plants genetic material combines and the resulting seeds from that pollination will have characteristics of both varieties and is a new variety. 
• Sometimes cross-pollinating is used intentionally in the garden to create new varieties. So option A is correct.

In pea, anthers and stigma are present close to each other therefore pollination is easy while in cross pollinating plants pollination takes place with the help of an external agency.

Heterostyly is the presence of $2-3$ types of flower with different heights of styles and stamens. In diheterostyly (dimorphic heterostyly), there are two types of flower, pin eyed (long style and short stamens) and thrum eyed(short style and long stamens), e.g., Primula vulgaris (primrose), jasmine.

• Emasculation is the removal of stamens or anthers or killing the pollen of a flower without the female reproductive organ is known as emasculation. In bisexual flowers, emasculation is essential to prevent self-pollination. In monoecious plants, male flowers are removed or male inflorescence is removed. 
• In species with large flowers e.g., (cotton, pulses) hand emasculation is accurate and it is adequate. In species with large flowers, removal of anthers is possible with the help of forceps. It is done before anther dehiscence. 
• The corolla of the selected flower is opened with the help of forceps and the anthers are carefully removed with the help of forceps. 
• An efficient emasculation technique should prevent self-pollination and produce a high percentage of seed set on cross-pollination.

In tobacco, due to the continuous self-pollination, homozygosity increases. It results in the occurrence of inbreeding depression, and the plants are called Inbred lines. When these inbred lines are subjected to hybridization, fertile hybrids are obtained. This is called Hybrid vigour or heterosis. This was developed by Kolreuter.

So, the correct option is ‘Kolreuter’.

Papaya plant is a dioecious plant. It prevents both autogamy and geitonogamy, which is a method of self pollination.

The species of birds and animals shows different types of isolation. The organisms which are located in the same habitat or geographical area but do not mate with each other. This type of isolation is known as the behavioral isolation in which different species have a different type of behavior with respect to reproduction. This prevents the interbreeding of the different species. 

The transfer of pollen from an anther of a flower of one plant to a stigma of a flower of another plant of the same species by the action of wind, insects etc is known as cross pollination. 

• Cross-pollination can be defined as the transfer of pollen grains from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. 
• Insects and wind act as the agents of cross-pollination.
• Cross-pollination helps to produce varieties in species by recombinant genes while self-pollination maintains homozygosity. 
  
• So the correct option is 'forms new varieties'. 
  

Mediterranean orchid Ophrys employs sexual deceit to ensure the cross pollination. In this process, one of the petals of the flower shows high resemblance with the structure of female bee. The male bee is deceived when it lands on the flower and tries to copulate with the petal. The male bee in the process of attempting pseudocopulation, carries pollen grains from one flower to the another.

Heterostyly is a form of polymorphism. In this condition, styles are of different lengths relative to the stamens in flowers. This reduces self pollination and promotes cross pollination. Primrose plants shows heterostyly.

Dichogamy : It is defined as the condition in some flowering plants, in which the pistils and stamens mature at different times, thus preventing self-pollination. In other terms, it is defined as the maturation of male and female parts of a flower at different times, preventing automatic self-pollination.

Herkogamy - common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male and female function. It differs from other such strategies by supplying a spatial separation of the anthers and stigma.

Herkogamy is a probable strategy applied by hermaphroditic angiosperms to reduce sexual interference between male and female function. It varies from other such strategies by supplying a spatial parting of the anthers and stigma.

Heterostyly is referring to the condition of having styles of different lengths, These are relative to the stamens in the flowers of various individual plants for reducing self-fertilization.

Dichogamy is the condition in which the male and female reproductive organs of the flower mature at different times to ensure that self-fertilization does not occur.

Cleistogamy refers to the self-fertilization which occurs within a permanently closed flower.

So option B is correct.

Because apomixis is a abnormal kind of sexual reproduction in which egg or other cells associated with egg (synergids, antipodals etc) develop into embryo without fertilization and with or without meiosis.

In heterostyly condition , stamens style and stigma are of different heights e.g., Primula , Oxalis , Linum etc .

Raphanobrassica , Triticale and Bromato are some  intergeneric hybrids. Raphanobrassica (Cabbage) is the result of distant cross between Raphanus (Radish) and Brassica (Cabbage). 

Cleistogamy is not a device to promote cross-pollination as the flowers remain closed and they promote self-pollination. For example, Balsam, Oxalis and Viola anthers dehisce inside closed flowers. 

In some plants when the stigma receives pollen from the same flower as well as from the other flower simultaneously, the foreign pollen germinates vigorously and fertilize the ovule.

Prepotency is the phenomenon in which Pollen grains of another flower of the same species germinate more rapidly over the stigma, in comparison to the pollen grains of the same flower. For example Apple, Grape, etc.

So the correct answer is D.

Self-incompatibility is the widespread mechanism in flowering plants which prevents the inbreeding and promotes the outcrossing. Dichogamy is the mechanism when the stigma and anther mature at different times.  Monocliny i.e. Bisexuality is applicable for bisexual flowers. Pollen prepotency is the mechanism when the pollen of a different flower germinates faster than of the same flower thus preventing autogamy.

Thus, the correct option is D.

Dichogamy- It is the condition when the anther and stigma mature at different times. Either anthers dehisce before the stigma becomes receptive (called protandry) or stigma becomes receptive before anthers dehisce (called protogyny).

Heterostyly- It is the occurrence of 2-3 types of flowers within the same plant and such flowers have the difference in length of styles and stamens.

Dichogamy- It is the condition when the anther and stigma mature at different times. Either anthers dehisce before the stigma becomes receptive (called protandry) or stigma becomes receptive before anthers dehisce (called protogyny).

In Adansonia cross pollination takes place through bat. This type of pollination is called chiropterophily.

Monoecious plants are those that have the male and female flower on the same plant. An example is maize.

Herkogamy is shown by hermaphroditic angiosperms to reduce sexual interference between anthers and female stigma function. Autogamy, or self-fertilization, refers to the fusion of two gametes that come from one individual. cleistogamy is self-fertilization that occurs within a permanently closed flower. Dichogamy means when stamens and stigma mature at different times favouring cross-pollination. 

In plants, allogamy is used specifically to mean the use of pollen from one plant to fertilize the flower of another plant and are usually synonymous with the term cross fertilization , though the latter can be used more specifically to mean pollen exchange between different plant strains or even different individuals. Allogamy is best favoured by Dicliny. Dicliny refers to unisexual flowers. This is of two types: monoecy and dioecy.

Continous self-pollination or inbreeding leads to inbreeding depression, a condition where the decrease in genetic vigor and vitality results in reduced fitness in offsprings.
Dichogamy is the condition in some flowering plants where the pistils and stamens mature at different times, thus preventing self-pollination.
It is of two types: protandry and protogyny.

Incapability of pollen grains of one flower to grow over the stigma of the same flower due to the presence of similar sterile genes is called self-sterility. Ex: Tobacco, Crucifers, Potato and Gramineae.

Incapability of pollen grains of one flower to grow over the stigma of the same flower due to the presence of similar sterile genes is called self-sterility. Which a leads to emasculation, sexual incompatibility, and cross-pollination.

Cross-pollination is when one plant pollinates a plant of another variety. The two plants' genetic material combines and the resulting seeds from that pollination will have characteristics of both varieties and is a new variety. Self-sterility in plants is enhanced to prevent self-fertilization and increase family diversification. Dichogamy is the ripening of the stamens and pistils of a flower at different times so that self-fertilization is prevented. Herkogamy is a common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male (anthers) and female (stigma) function. Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, exist in the population. All these prevent self-pollination and favour cross-pollination.

Heterostyly is the occurrence of 2-3 types of flowers within the same plant. Such flowers have a difference in length of styles and stamens.

Protandry is the condition when anthers mature before the stigma becomes receptive is called protandry. So, the condition in which the male reproductive organs of a flower mature before the female ones, and hence ensuring that self-fertilization does not occur.

Dicliny is the presence of only one kind of reproductive whorl in a flower.

Herkogamy is the condition in which the flower structure is such that even being bisexual. In some flowers, a mechanical barrier exists and thus self-pollination is not possible. Sometimes, there is a hood for covering the stigma.

So, the correct answer is B.