Air is an example of
mixture
The explanation for the correct answer -
(C) Mixture - when two or more substances are mixed physically in any random proportion in such a way that they retain their individual properties is called a mixture.
Air is an example of a mixture. It is composed of many gases.
The explanation for incorrect answers -
(A) Element - It is a pure substance made up of atoms of the same kind and cannot be separated by any chemical method.
For example - nitrogen, hydrogen, iron, copper, etc.
(B) Compound - It is a pure substance made by a chemical reaction of two or more elements in a fixed proportion.
For example - common salt, sugar, water, etc.
Hence, option (C) is correct. Air is an example of a mixture.