Answer:
c. Carbon Dioxide
Step-by-step explanation:
The rate of respiration is determined by the presence of concentration of carbondioxide gas in the blood because in the process of respiration, energy in the form of adenine tri phosphate (ATP) and carbondioxide gas are produced. This ATP is required for performing different activities while carbondioxide gas is a waste product which must be removed from the blood through breathing. If carbondioxide gas is produced quickly so the rate of respiration is also increased in order to remove the gas from the blood.