During photosynthesis, plants convert light energy into chemical energy stored in glucose. The statement "plants do not use up energy; they merely convert it from light energy to chemical energy" desc

During photosynthesis, plants convert light energy into chemical energy stored in glucose. The statement "plants do not use up energy; they merely convert it from light energy to chemical energy" describes the principle that energy cannot be created or destroyed, only transformed from one form to another. This is the definition of the first law of thermodynamics, also known as the law of conservation of energy.

The correct option is:

• the first law of thermodynamics.