The substance that carries energy to the Calvin cycle is NADPH, which donates electrons for synthesizing glucose. Other options like ADP, O₂, and H₂O do not serve this specific role in the process. Therefore, the correct choice is A. NADPH.
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The substance that carries energy to the Calvin cycle is NADPH , which supplies the necessary electrons for synthesizing glucose from carbon dioxide. Other options do not function as energy carriers in this process. Understanding NADPH's role is crucial for grasping photosynthesis. ;