Which of the following mathematical combinations of respiratory volumes correctly represents the volume of air that will remain in the lungs after a normal expiration?

Step-by-step solution

The volume of air that will remain in the lungs after a normal expiration is known as the Functional Residual Capacity (FRC). According to NCERT, FRC includes the Expiratory Reserve Volume (ERV) and the Residual Volume (RV). Therefore, it is mathematically represented as ERV + RV . TV + ERV represents Expiratory Capacity (EC). ERV + RV + TV represents the sum of FRC and Tidal Volume, which is not a standard defined capacity. Answer: ERV + RV