The correct option is D HMP shunt
During Calvin cycle, NADH2 are not produced.
During Krebs cycle, 2 NADH2, 1 FADH2, 1GTP are produced.
During EMP pathway 2 NADH, 2 ATP are produced.
During HMP pathway, NADPH2 are produced. So, in respiratory cycle mainly NADPH2 are produced is HMP pathway. Thus, option D is correct.