Explanation :
The graph shows the variation of heat absorbed with temperature. The process takes place in five steps.
Water exists in three forms:
Section B shows the melting of water. When the solid ice converts into a liquid state the process is called melting. Here, the temperature is constant. The melting point of ice is
. It shows that the ice is converting to water (at
).
So, the correct option is (c) " melting ".