Read the following scenario to answer the following question. An abundant and continual supply of ATP is necessary for all living cells. Active muscle cells require an extraordinary amount of ATP to permit strenuous exercise for prolonged periods. Toxins, reduced blood flow, and a compromised respiratory system can interfere with the transport of oxygen to active cells. A runner in a marathon faces multiple obstacles to continue to produce sufficient ATP to remain competitive. Breathing faster when we exercise is necessary to expel .

Carbon dioxide and also bring in more oxygen for supporting the aerobic metabolism

Explanation:

 The aerobic metabolism is one of the type of process in which the body basically helps in creating the energy in our body by the process of combustion of the fats and carbohydrates in the oxygen presence.

According to the given scenario, when we doing exercise the breath become more faster and at that specific time it is very important to expel the carbon dioxide and then inhale more oxygen for supporting the aerobic metabolism in the our body system.

 Therefore, The given answer is correct.