Answer: The correct answer is-
C. A decrease in the production of ATP.
Photosynthesis is a process of formation of food by green plants and algae using CO2 and water in the presence of sunlight. It is primarily divided into two phases that is -
1) light dependent phase ( Hill's reaction) and 2) light independent phase ( calvin cycle).
Light dependent phase is the first phase in which chlorophyll first absorbs energy from sunlight and convert it into chemical energy in the form of ATP and NADPH.
ATP and NADPH is further utilized in the calvin cycle ( light independent phase, which is the next phase of photosynthesis) in order to synthesize food ( glucose, which is a carbohydrate).
If a plant does not receive enough sunlight, there will be decrease in the production of ATP because it is associated with the first phase of photosynthesis that is the light dependent phase.
Thus, option C) is the right answer.