Physiology The functional residual capacity is best defined as the sum of : A Tidal volume and Inspiratory Reserve volume B Residual Volume and expiratory Reserve Volume C Residual Volume and Inspiratory reserve Volume D Tidal volume , Inspiratory Reserve volume and Expiratory Reserve Volume 💡 Explanation The functional residual capacity is best defined as the sum of : ✓ Correct Answer: B. Residual Volume and expiratory Reserve Volume