Which law states that energy cannot be created or destroyed?

The correct answer is the Law of Conservation of Energy, which asserts that energy in a closed system cannot be created or destroyed, but it can be transformed from one form to another. For instance, when potential energy is converted into kinetic energy, the total energy in the system remains constant. This principle is fundamental in understanding various scientific concepts, including mechanics, thermodynamics, and many natural processes.

The other options refer to different principles. The Law of Thermodynamics encompasses multiple laws relating to heat, energy transfer, and entropy but is not specifically focused on the conservation aspect. The Law of Conservation of Mass states that mass in a closed system remains constant over time, which highlights a different aspect of physical science. Newton's First Law, which addresses the motion of objects and the tendency of an object to remain in its state of motion unless acted upon by an external force, does not pertain directly to energy conservation. The distinction is essential for a clear understanding of each law's role in science.