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: Social & Preventive Medicine
[{'content': 'Under passive surveillance for tuberculosis, indication for sputum microscopy cough is for weeks or more \nSelect and explain. \nA. 8 weeks, B. 4 weeks, C. 6 weeks, D. 3 weeks', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]