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: Surgery
[{'content': 'Spontaneous pneumothorax exceeding ……………. % of chest cavity should have a chest tube inserted - \nSelect and explain. \nA. 10, B. 25, C. 45, D. 60', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Exact answer according to Schwartz in 30%.', 'role': 'assistant'}]