When components do not combine chemically, it is a compound substance mixture molecule

Option (c) is the correct answer.

When an atom donates or shares its valence electrons with other atoms then it results in the formation of a new atom. This means a chemical has occurred as the chemical composition of products will be different from the reactants.

Whereas a substance is a matter which contains specific composition with some specific properties.

When two or more substance are mixed together then it is known as a mixture. It is not necessary that substances added will combine with each other.

When atoms of similar element chemically combine together then they result in the formation of a molecule.

For example,

Therefore, we can conclude that when components do not combine chemically, it is a mixture.