This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
Residual volume is the volume of air in lung after 
Select and explain. 
A. Maximal inspiration, B. Maximal expiration, C. Normal inspiration, D. Normal Expiration
B: Maximal expiration
Answer: B: Maximal expiration 
Explanation: The air left in the lungs after a maximal expiratory effo is the residual volume.Ref: Ganong review of medical physiology 23rd edition Page no: 593