Final answer:
During moderate aerobic exercise, the ERV changes more compared to normal breathing.
Step-by-step explanation:
In moderate aerobic exercise, the respiratory rate and volume of air per breath change. The expiratory reserve volume (ERV) is the amount of additional air that can be exhaled after a normal exhalation, and the inspiratory reserve volume (IRV) is the amount of additional air that can be inhaled after a normal inhalation.
During moderate aerobic exercise, the ERV changes more compared to normal breathing. This is because the body requires more oxygen during exercise, so the respiratory rate increases while the ERV decreases to accommodate the increased oxygen demand.
Therefore, the correct answer is A. ERV changed more.