In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?

A. addition of a pair of electons from NADPH
B. regeneration of ATP from ADP
C. regeneration of RuBP
D. regeneration of NADP+
E. inactivation of RuBP carboxlyase enzyme