Which Labeled Group Is Active in the Redox Function of the Cofactor

Multiple Choice

Which labeled group is active in the redox function of the cofactor shown in Figure 5.1, and in which pathway is it most important?

A) Label I; transaminations.
B) Label II; tricarboxylic acid (TCA) cycle.
C) Label III; glycolysis.
D) Label IV; oxidative phosphorylation.
E) Label V; folate cycling.