1. The problem asks about the purpose of light reactions in photosynthesis. 2. Light reactions are the first stage of photosynthesis where light energy is converted into chemical energy. 3. The main purpose of light reactions is to convert light energy into chemical energy in the form of ATP and NADPH. 4. During this process, water molecules are split (photolysis), releasing oxygen as a byproduct. 5. Light reactions do not produce water or sucrose, nor do they convert carbon dioxide to glucose; these occur in the Calvin cycle (dark reactions). 6. Therefore, the correct purpose of light reactions is to convert light energy to oxygen and chemical energy carriers. Final answer: The purpose of light reactions is to convert light energy to oxygen and chemical energy (ATP and NADPH).