ANS:D - all (a), (b) & (c)

The internal energy of a substance comprises all of the following types of energy:

1. Vibrational energy: This refers to the energy associated with the vibration of atoms or molecules within a substance. In solids, molecules vibrate about their equilibrium positions.
2. Rotational energy: This refers to the energy associated with the rotation of molecules around their axes. In gases and liquids, molecules can rotate about their centers of mass.
3. Translational energy: This refers to the energy associated with the movement of molecules through space. In gases, molecules move freely and randomly in all directions.