I think the answer is c hope is right
In aerobic respiration, the final electron acceptor in the electron transport chain is oxygen. It accepts two electrons and a molecule of water is formed as a by product.
In anaerobic respiration, the final electron acceptor in the electron transport chain is pyruvate. Anaerobic respiration commonly occurs in the muscle tissue of animals as a result of intense activity or exertion. Pyruvate is used as makeshift electron acceptor in place of oxygen and is reduced or converted to lactic acid.
Because humans can not stay the same forever
C. Oxygen and nutrients taken in by the respiratory system are transported to the circulatory system for transport around the entire body.
Also, B and D cannot be correct, as carbon dioxide is not wanted in the body (it's a waste product of respiration of the body cells)