Answer: Option (a) is the correct answer.
Step-by-step explanation:
Change in state of a substance occurs due to change in position of atoms by absorption or release of heat energy.
For example, ice is the solid state of water and when we keep it at room temperature then it absorbs heat from its surroundings. As a result, intermolecular forces of attraction between its molecules weaken.
Due to this particles or atoms gain kinetic energy and they tend to move away from each other.
Thus, we can conclude that a change from one state of matter to another involves the transfer of heat.