The correct option is C Pyruvic acid
Aerobic respiration requires oxygen in order to generate ATP. Although carbohydrates, fats, and proteins are consumed as reactants, it is the preferred method of pyruvate breakdown in glycolysis and requires that pyruvate enter the mitochondrion in order to be fully oxidized by the Krebs cycle. Aerobic respiration includes, glycolysis, TCA cycle and ETS, where the intermediate is pyruvic acid. In anaerobic respiration pyruvic acid is also an intermediate product. So, the correct answer is B.