The changing of solid into liquid on heating, is called___________.
melting
Melting: The process in which solids change to a liquid is called melting. The melting point is the temperature at which solids change to a liquid.
Explanation for Incorrect option:
Fusion: Fusion is not a state of matter. It is the name of one of the processes that cause a change from one state of matter to another.
Hence the correct option is A