The best explanation for how the systems in the human body work together to maintain homeostasis and remove excess carbon dioxide during exercise is:
A. The respiratory system takes in more oxygen, and the blood transports the oxygen and carbon dioxide to and from the tissues.
This option accurately describes the coordination between the respiratory system, which increases oxygen intake during exercise, and the circulatory system, which transports oxygen to the tissues and carries carbon dioxide, a waste product of metabolism, back to the lungs for exhalation.