This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Volume of lung after maximal forceful expiration ? 
Select and explain. 
A. Tidal volume, B. Residual volume, C. Inspiratory reserve volume, D. Expiratory reserve volume
B: Residual volume
Answer: B: Residual volume 
Explanation: Ans. is 'b' i.e., Residual volume