The following statements describe the change in kinetic and potential energies of a substance while changing temperature or state.
I. The kinetic energy and potential energy both increase while the substance melts.
II. The potential energy increases while the kinetic energy stays constant while the substance melts.
III. The kinetic energy increases while the potential energy stays constant when the temperature of the substance increases.
IV. The kinetic energy and potential energy both increase when the temperature of the substance increases.
Tell which of the above statement(s) is / are true? (C)