Answer:
The correct answer is C. oxygen
Explanation:
Aerobic respiration occurs in the presence of oxygen. So aerobic organism requires oxygen in order to gain energy. This oxygen act as the final electron acceptor in the electron transport chain and by doing this it helps in the production of ATP.
So in aerobic respiration without oxygen, no production of ATP or no energy production can occur but in anaerobic respiration, oxygen is not present therefore other molecules like sulfur, nitrate, etc are used as electron acceptor. So the correct answer is C. oxygen
