the Calvin cycle proceeds in three stages: carboxylation, reduction, and regeneration . The Reduction stage involves a series of reactions that lead to the formation of glucose. The text explicitly states: "The steps involve utilisation of 2 molecules of ATP for phosphorylation and two of NADPH for reduction per CO2 molecule fixed" . The regeneration step requires an additional 1 ATP, making the total requirement 3 ATP and 2 NADPH per CO2 , but the question specifically asks about the reduction phase.