The right answer is C
In the anaerobic mode, the reduction of pyruvate to lactate or ethanol (fermentations) ensures the reoxidation of NADH to NAD + consumed during the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate (reaction 6 of glycolysis). This regeneration of NAD + allows glycolysis to be maintained in the absence of oxygen.
In the aerobic mode, NAD + is regenerated by the respiratory chain.
