Answer:
B. NAD+ is formed by a fermentation process in anaerobic respiration by the conversion of pyruvate into lactate and by simple oxidation of NADH in aerobic respiration.
Step-by-step explanation:
Nicotinamide adenine dinucleotide (NAD) is an important coenzyme that may exist in two different forms: oxidized (NAD+) and reduced (NADH). The fermentation is an anaerobic oxidation-reduction reaction where pyruvate and NADH are reactants, while lactate and NAD+ are products generated by the oxidation of NADH to NAD+ and pyruvate to lactate, respectively. On the other hand, during aerobic respiration, NADH generated by glycolysis is oxidized to form NAD+ by the donation of its electrons to reduce pyruvate to lactate. Subsequently, NAD+ is reused in glycolysis (again) in order to generate more molecules of ATP.