The correct option is A. They provide the energy required to build high-energy sugars.
Explanation:
Calvin cycle can be described as the series of dark reactions of the process of photosynthesis.
During the Calvin cycle, carbon dioxide is reduced to glucose. The molecules of NADPH and ATP play an active role in this reaction to occur. The molecules of ATP serve as a source of energy. Whereas, the molecules of NADPH serve as a reducing agent. Electrons are added by NADPH so that carbon dioxide gets converted into glucose.
