Why is proper ventilation important for a respiring animal?
A) It directly increases gas exchange between the blood and cells. B) It maintains blood circulation within the body of an animal. C) It maintains proper O2 and CO2 levels on the internal side of the respiratory surface so that diffusion across it can be maintained. D) It maintains proper O2 and CO2 levels on the external side of the respiratory surface so that diffusion across it can be maintained.