I’m assuming this entire thing is cellular respiration. pathway a most likely represents alcoholic fermentation, B represent lactic acidosis fermentation, C probably represents aerobic cellular respiration. Alcoholic fermentation doesn’t occur in humans, it occurs in micro bacteria and yeast. Lactic acidosis fermentation occurs in humans when there is not oxygen. That’s why you breathe so heavily after sprinting. Cellular respiration just happens naturally. Idk if that’s what the question is asking so feel free to comment and if this helped, brain answer?