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
[{'content': 'Surfactant contains? \nSelect and explain. \nA. DPCC, B. Nitros oxide, C. Angiotensin, D. VIP', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The low surface tension when the alveoli are small is due to the presence in the fluid lining the alveoli of surfactant, a lipid surface-tension-lowering agent. Surfactant is a mixture of dipalmitoylphosphatidylcholine (DPPC), other lipids, and proteins.Ref: Ganong review of medical physiology 23rd edition Page no: 597', 'role': 'assistant'}]