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': 'HIV prevalence can be assessed by- \nSelect and explain. \nA. Sentinel surveillance, B. Active, C. Passive, D. Register', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Sentinel surveillance o Sentinel surveillance in India is done in national AIDS control programme.", 'role': 'assistant'}]