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: Medicine
[{'content': 'Spontaneous pneumothorax is commonly seen in: \nSelect and explain. \nA. Smokers, B. Young females, C. Old age, D. Sho statured men', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (smokers): Spontaneous pneumothorax is common in smokers. Spontaneous pneumothorax characteristically affect young, tall and thin men/boys (male gender).', 'role': 'assistant'}]