Mixtures are classified as homogeneous and heterogeneous according to
the distribution of their components
whether their components are elements or compounds
the masses of their components
the states of matter of ther components

Option (a) is the correct answer.

Explanation:

A mixture is defined as the substance that contains two or more different number of substances that are physically mixed together.

For example, a mixture of iron nails, sand and water.

A mixture in which solute particles are unevenly distributed into the solvent then it is known as a heterogeneous mixture.

For example, sand in water is a heterogeneous mixture.

A homogeneous mixture is defined as the mixture in which solute particles are evenly distributed in a solvent.

A homogeneous mixture is a clear solution.

For example, salt dissolved in water is a homogeneous mixture.

Thus, we can conclude that mixtures are classified as homogeneous and heterogeneous according to the distribution of their components.

c (diamond),

sio2 (quartz)