The correct answer to the question is B) Absorbing energy.
EXPLANATION:
As per our question, the substance is melting at constant pressure.
Melting is a process of phase change in which a solid substance is converted into liquid at its melting point. For instance, melting of ice.
The thermal energy of the liquid is more as compared to solid. Hence, the solid must have to absorb energy to be converted into liquid. The absorbed energy will be utilized in changing the solid into its corresponding liquid.
As melting is a process of phase change or state change, the temperature of the substance will be constant as long as total solid is not converted into liquid. Hence, the kinetic energy of the substance will be constant. So, the energy absorbed during melting will only change the configuration of the substance i.e the absorbed energy is converted into potential energy of the system.
Hence, the correct answer of the question is that energy is absorbed during melting.
