This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: New Born Infants, Subject name: Pediatrics
Lungs do not collapse during expiration because of the presence of? 
Select and explain. 
A. Hyaline membrane, B. Dipalmitoyl phosphatidyl choline, C. Macrophages, D. Interstitial fluid
B: Dipalmitoyl phosphatidyl choline
Answer: B: Dipalmitoyl phosphatidyl choline 
Explanation: b. Dipalmitoyl phosphatidyl choline(Ref: Ghai 8/e p 169-170)Dipalmitoyl phosphatidyl choline is an important constituent of Surfactant, which prevent alveolar collapse during expiration.