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
[{'content': 'Which of the following is the major constituent of the lung surfactant? \nSelect and explain. \nA. Mucoprotein, B. Phospholipids, C. Fibrinogen, D. Fibrin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Nearly 77% of surfactant is composed of phospholipids.', 'role': 'assistant'}]