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': 'Sputum examination for AFB is a type of- \nSelect and explain. \nA. Primary prevention, B. Secondary prevention, C. Teiary prevention, D. Primordial prevention', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Secondary prevention Sputum for AFB is used for diagnosis of TB, so that treatment can be staed", 'role': 'assistant'}]