The heat energy required to change a substance from a solid to a liquid at its melting point is called the latent heat of fusion. This is because the temperature of the substance does not change during the melting process, but energy is still required to overcome the forces holding the particles in the solid state. In contrast, the latent heat of vaporization is the heat required to change a substance from liquid to gas, while specific heat is the amount of heat needed to raise the temperature of a substance.
The correct option is (C): latent heat of fusion