Correct Answer: The law of conservation of energy

Solution : The correct option is The law of conservation of energy.

The law of conservation of energy is used in the first law of thermodynamics. According to it, energy can only alter its form and cannot be created or destroyed in a closed system. According to thermodynamics, this implies that energy can be exchanged between different forms (such as heat, work, or potential energy) but the overall amount of energy within a closed system remains constant.