The correct option is A residual volume
Residual volume (RV) is the volume of air remaining in the lungs after forceful expiration. In other words, it is the volume of air that cannot be expelled, thus causing the alveoli to remain open at all times. This prevents the lungs from collapsing. Values for residual volume are 1 to 1.2 L, but these values are dependent on factors including age, gender, height, weight, and physical activity levels.
Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle during normal breathing. The normal value is approximately 500 mL.
Inspiratory reserve volume (IRV) is the additional volume of air that a person can inspire by a forcible inspiration.
Expiratory Reserve Volume (ERV) is the additional volume of air that a person can expire by a forcible expiration.