Question

The reaction responsible for the production of light energy from the sun is

Answer 1

Nuclear fusion.

According to Wikipedia "In nuclear chemistry, nuclear fusion is a reaction  in which two or more atomic nuclei  are combined to form one or more different atomic nuclei and subatomic particles (neutrons  or proton). The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference in mass arises due to the difference in atomic "binding energy" between the atomic nuclei before and after the reaction. Fusion is the process that powers active or "main sequence" stars, or other high magnitude stars"