Difference in weight this process is called winnowing option A is not correct Option B difference in colour that's type B is not correct Option C is now check Option C is not correct difference in shape Option D difference in size is correct

The correct answer is option 'D', difference in size. Sieving is a method of separating mixtures based on the difference in size of the particles. It is a commonly used technique in various industries such as mining, construction, and agriculture.

Sieving involves passing a mixture through a sieve, which is a device with uniform holes or pores of a specific size. The particles that are smaller than the size of the sieve openings pass through, while larger particles are retained. This separation is achieved due to the principle that particles with sizes smaller than the sieve openings can fit through, whereas larger particles cannot.

Here is a detailed explanation of why the property of difference in size forms the basis of sieving:

1. Principle of Sieving:
- Sieving works based on the principle that particles smaller than the sieve openings will pass through, while larger particles will be retained.
- The size of the sieve openings determines the size of particles that can pass through.

2. Importance of Particle Size:
- Particles in a mixture can have different sizes, ranging from large to small.
- The size of particles affects their properties, behavior, and uses.
- Sieving is particularly useful for separating mixtures where particle size is a distinguishing factor.

3. Separation Based on Size:
- When a mixture is poured onto a sieve, the smaller particles will fall through the sieve openings due to gravity.
- The larger particles will be retained on top of the sieve.
- By carefully selecting the appropriate sieve size, it is possible to separate particles of different sizes.

4. Applications of Sieving:
- Sieving is used in various industries for different purposes.
- In mining, sieving is used to separate valuable minerals from the ore.
- In construction, sieving is used to separate different sizes of aggregate for concrete production.
- In agriculture, sieving is used to separate grains and seeds of different sizes.

In conclusion, the property of difference in size forms the basis of sieving. By using sieves with different opening sizes, particles of different sizes can be separated effectively. Sieving is a widely used method for separating mixtures and has numerous applications in various industries.