The correct option is C 10
During cellular respiration, complete oxidation of glucose takes place through glycolysis and Krebs cycle.
In the process of glycolysis, 6 carbon compound of glucose (1 molecule) splits into two 3 carbon compounds of pyruvic acid (2 molecules), In this process, 2 molecules of NADH are generated.
During Krebs cycle, for every pyruvic acid that enters the pathway, 4 molecules of NADH are produced. Since 2 pyruvic acid molecule are produced during glycolysis, a total of 8 NADH are produced in krebs cycle.
Therefore, during the complete oxidation of glucose, a total of 10 NAD molecules are reduced to NADH.
The energy stored within the NADH is released in the form of ATP during the electron transport chain.