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': 'Case finding in RNTCP is based on – \nSelect and explain. \nA. Sputum culture, B. Sputum microscopy, C. X-ray chest, D. PCR antibody detection', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "Sputum microscopy not only confirms the diagnosis, but also indicates the degree of infectivity and response to treatment" - Park\nRemember\n\nAt least 10000 (104) bacilli should be present per ml of sputum for demonstration in direct smear on ZN staining\nCulture can detect 10-100 bacilli per ml of sputum', 'role': 'assistant'}]