Answer: Option (c) is the correct answer.
Explanation:
Chemical changes are defined as the change which tend to show difference in chemical composition of a substance.
For example, toxicity, reactivity, combustion etc are all chemical properties.
A chemical change will always lead to the formation of a new compound and this change is irreversible in nature by any physical means.
A release or absorption of heat energy can take place in a chemical change.
On the other hand, a change which is unable to bring any difference in chemical composition of a substance is known as a physical change.
For example, change in shape, size, mass, volume etc are all physical properties.
Physical changes are reversible in nature.
Thus, we can conclude that the release or absorption of energy indicate chemical change.
