Final answer:
The process of ice being heated and turning into water is called melting, which requires energy to break the bonds between the molecules.
Step-by-step explanation:
When ice is heated and turns into water, the phase change occurring is called melting. This process requires energy to break the bonds between the ice molecules, transitioning the substance from a solid to a liquid state. The correct answer to the question is thus: (a) Melting - Requires energy. During melting, there is no rise in temperature until all the ice has converted into water. The phase changes to a more energetic state, which includes melting, vaporization, and sublimation, all require the input of energy.