Light reaction of photosynthesis produces ATP.
Option A
Explanation:
Light reaction is first stage of photosynthesis. The chlorophyll absorbs the energy from the sunlight. The energy releases in the form of ATP.
The energy is then used by the two molecules ATP and NADPH which are used in second stage of "photosynthesis". "ATP and NADPH" are generated by two electron transport chains. During the light reactions, water is used and oxygen is produced. The light reactions occurs in the day time only because the light reactions need sunlight.