What happens to the body when there is an increase in metabolic rate during exercise?

When the body engages in exercise, there is a significant increase in metabolic rate to meet the higher energy demands. This metabolic increase results in the production of more carbon dioxide and a greater consumption of oxygen, requiring an efficient response from the respiratory system.

As a consequence of this increased metabolic activity, expired ventilation, which reflects the amount of air expelled from the lungs after breathing, also increases. This is because the body must eliminate the excess carbon dioxide that is generated and simultaneously obtain more oxygen to support the aerobic processes. The respiratory rate and depth of breathing increase to accommodate this heightened demand, resulting in a greater volume of expired air.

The other choices do not align with the physiological responses associated with an increase in metabolic rate during exercise, where ventilation rates typically rise to ensure proper gas exchange and to meet the metabolic demands of the working muscles.