No, we cannot separate powdered salt and sugar by winnowing beacuse they are forming homogeneous solution.

As iron can be attracted by magnets, so magnetic separation method method can be used to separate iron from the mixture.

Ammonium chloride sublimes on heating therefore it is easy to remove it by sublimation from a mixture of ammonium chloride and potassium chloride.

The two solid mixtures, one of which dissolves in a particular solvent and other does not, can be separated by solvent extraction method.

Magnetism is a form of separating mixtures which involves using a magnet to attract another magnetic object away from the substance it is in. Iron gets attracted towards magnet and are separated from brass.

A mixture with iron filings as one of the components can be separated using a magnet to attract the iron particles away from the mixture.

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet.

Fractional distillation is used to separate two liquid mixture based on difference in their boiling point.

The separation of solid particles based on size is known as screening.

To separate elements X and Y from the compound XY we have to break it into ions,

Handpicking, winnowing, sieving, sedimentation, decantation and filtration are some of the methods of separating substances from their mixtures. 

 Sieving allows the fine flour particles to pass through the holes of the sieve while the bigger impurities remain in the sieve.

Since X, Y can be separated by magnetic separation so X, Y are solids. 

X, Y are two solids making a mixture. 

Napthalene can be dissolved in a solvent like benzene and filtered from iron filings. On evaporating the solution napthalene can be obtained back. This method is solvent extraction.
Iron filings can be attracted towards magnet and separated from napthalene. Therefore, method can be used magnetic separation.
Napthalene has the property of sublimation hence on heating napthalene sublimes and gets separated from iron filings by the method of sublimation.

Mixed melting point is considered to be the best criteria for purity of a substance. The purified sample is mixed with a small quantity of pure compound and melting point of mixture is determined. If melting point of mixture is same as that of the pure compound, the sample compound is pure, otherwise it requires further purification.

Solvent extraction is a method used for separating a substance from one or more by using a solvent.

Electrical and Magnetic separation: Electrolytes and non electrolytes, magnetic and non magnetic substances can be separated by this technique of separation using either electrical field or magnetic field.
Magnet can be used to separate iron from sulphur.

A farmer uses the method of threshing to separate the grain from the stalks. The stalks are beaten to separate the grain seeds.

Since the size of glass particles is bigger than sugar, so we can easily get rid of those by hand picking.

By magnetic separation- It is used to remove particle Z because Z is iron.

Threshing is the process of loosening the edible part of grain from the husks and straw to which it is attached. 

Winnowing is a farming method developed by ancient people for separating grain from the chaff. It is also used to remove weevils or other pests from stored grain. Threshing, which is the loosening of grain or seeds from the husks and straw, comes before winnowing. It is used for heterogeneous solid-solid mixtures.

winnowing is used to separated heavier and lighter components of a mixture by wind or by blowing air.This process is done by the farmers to separated lighter husk particles from heavier grain particles.

Winnowing is a farming method developed by ancient people for separating grain from chaff. It is also used to remove weevils or other pests from stored grain. Threshing, which is the loosening of grain or seeds from the husks and straw, comes before winnowing. It is used for heterogeneous solid-solid mixtures.

Sieving can be used only when the components of the mixture are of different sizes.

In a mixture of two materials if one have magnetic properties then that material is easily separate by magnet because that material attracted by magnet and other material is not attracted by magnet. 

Iron sulphide is not attracted towards magnet whereas its element (iron) is attracted towards magnet. This suggests that properties of compound are different to the properties of its constituents. In words, magnetic iron on chemical combination with sulphur, gives non magnetic iron sulphide.

To obtain dry sample of NaCl from sand, first we have to dissolve it in water;

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet.

Winnowing is a method of separation of chaff or husk from wheat/grains. Also called the process of separation of heavier components from lighter components by the application of wind.

Hand picking is a method of separation used where one of the component is in small quantity. And it is best for mixture of solids, for eg- Stone in rice.

Advantages of Handpicking Method:-

Winnowing- Winnowing is a method of separation of chaff or husk from wheat/grains. Also called process of separation of heavier components from lighter components by the application of wind.

Freezing point is the temperature where a liquid converts into solid. Water converts into ice at zero degrees centigrade. So degree zero centigrade is the freezing point of water. Hence option $D$ is correct.

If the size of particle it too small to be picked by hand,sieving is used for separating substances. A sieve; having pores of certain  size is used. The bigger particles are retained by the sieve whereas the smaller particle are passed  through it. For example; this method is used for separating bran from flour, sand from gravel, pearls of different sizes,etc.

Threshing is used for separating seeds from the harvested stalks.

Combine harvesters are machines which harvest, threshes and winnows in a single operation. Combine harvesters are used in developed countries like the USA. In India, these machines can be seen in the farms of Punjab.

The process of separation of lighter particles from heavier particles; with the help of wind; is called winnowing. This method is used for separating grains from husk.
Hence option A is correct.