This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concept of health and disease, Subject name: Social & Preventive Medicine
[{'content': 'HIV prevalence can be assessed by \nSelect and explain. \nA. Sentinel surveillance, B. Active surveillance, C. Passive surveillance, D. Register', 'role': 'user'}, {'content': 'Answer: A \nExplanation: HIV Surveillance: 1) HIV Sentinel surveillance 2) HIV Sero-surveillance 3) AIDS case surveillance 4) STD Surveillance 5) Behavioral surveillance and 6) Integration with surveillance of other diseases like tuberculosis, etc. Ref: Park&;s Textbook of Preventive and Social Medicine, 24th edition, Page no. 452', 'role': 'assistant'}]