Which of the following stimuli is the most powerful respiratory stimulant to increase respiration?

A) arterial pH

B) an increase in blood pH

C) rising carbon dioxide levels

D) a rise in body temperature

Rising carbon dioxide level in the blood is mainly due to increased respiration in tissues. The carbon dioxide excreted by cells dissolves in blood plasma producing carbonic acid that lowers blood pH. A homeostatic response of the body will be increase respiration rate to expel the excess carbon dioxide from the body so as to maintain a normal 7.35-7.45 pH.