The number of CO₂, NADPH, and ATP molecules, respectively, required for one Calvin cycle is:

Explanation

The Calvin cycle is a series of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. For one cycle, which incorporates one carbon atom from CO₂, 3 molecules of ATP and 2 molecules of NADPH are consumed. Therefore, to complete one full cycle using three carbon atoms (to make glyceraldehyde-3-phosphate, a precursor to glucose), a total of 9 ATP and 6 NADPH are required. The other options either reflect the requirements for multiple cycles or are incorrect based on the cycle's stoichiometry.