Final answer:
The total energy of a closed system remains constant according to the law of conservation of energy, meaning it will remain the same as the potential energy it started with because there's no exchange with the surroundings.
Step-by-step explanation:
According to the law of conservation of energy, the correct statement that describes the total energy of a closed system at point b is (c) the total energy will remain the same as the potential energy it started with because no energy is exchanged with the surroundings. When considering a closed system, the law of conservation of energy dictates that the total energy within that system remains constant. It can be transformed from one form to another, such as from kinetic energy to potential energy or vice versa, but the total amount of energy is conserved.The first law of thermodynamics echoes this principle by stating that the internal energy of an isolated system remains constant as long as it does not exchange energy with its surroundings. Therefore, the internal energy -- the sum of kinetic and potential energies within the system -- must equal the initial potential energy when the distance of closest approach is reached, and kinetic energy becomes zero.