This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 1, Subject name: Physiology
A man has intrapleural pressure of (-5 cm H20) before inspiration and (-10cm H20) at the end of inspiration and he inspires 1200 ml from a spirometer. What shall be the the compliance of lungs? 
Select and explain. 
A. 50, B. 120, C. 240, D. 250
C: 240
Answer: C: 240 
Explanation: Compliance is change in volume per unit change in pressure. C= DV/DP DV= 1200 mL DP= -10-(-5) = - 5cm of H2O The minus sign indicates that the pressure has fallen by 6 cms of H20 at the end of inspiration Therefore the compliance is, C= 1200/5= 240 mL/cm of H2O