Residual volume refers to
Volume of air remaining in the lungs even after a forcible expiration
Volume of air inspired or expired during normal respiration
Additional volume of air, a person can expire by a forcible expiration
Additional volume of air, a person can inspire by a forcible inspiration
Respiratory Volumes -
Residual Volume (RV): Volume of air remaining in the lungs even after a forcible expiration. This averages 1100 mL to 1200 mL.
Hence, the correct option is a. Volume of air remaining in the lungs even after a forcible expiration