This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Functional Anatomy - Respiratory System, Subject name: Physiology
Normal residual volume is - 
Select and explain. 
A. 500ml, B. 1200ml, C. 3000ml, D. 2400ml
B: 1200ml
Answer: B: 1200ml 
Explanation: Ans. is 'b' i.e., 1200 ml