Answer:
b
Step-by-step explanation:
The law of conservation of energy states that energy can neither be created or destroyed, it can either be transformed from one form to another (For example from potential energy to kinetic energy) or transferred from one object to another (Example: When particles collide with each other, there is a transfer of energy between them, some of it is also lost as forms like heat to the surrounding).
Consequently, for a closed system(in which energy does not come from an external source), total amount of energy is always same.