Final answer:
Internal energy is the sum of potential and kinetic energies of the particles in a substance, including all forms of energy within a substance. The correct answer is C.internal Energy.
Step-by-step explanation:
The type of energy that refers to the sum of potential and kinetic energies in the particles of a substance is known as internal energy. Internal energy is a combination of the energy associated with the motions of atoms and molecules (kinetic energy) as well as the energy stored within the chemical bonds and forces that hold molecules together (potential energy). It essentially accounts for all possible forms of energy present in a substance, including thermal energy which is a subcategory of internal energy and relates to the average kinetic energy of the particles.