The correct answer is option [C] Boiling. Boiling is the process where a substance changes from its liquid state to vapor state throughout the bulk of the liquid, typically occurring at a specific temperature called the boiling point. Option [A] Melting refers to the solid-to-liquid phase transition. Option [B] Evaporation involves the conversion of a liquid into vapor at the surface, while boiling occurs throughout the liquid. Therefore, option [C] accurately describes the change of state from liquid to vapor. Option [D] None of these is incorrect as boiling specifically denotes this transition.