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': 'Follow-up ofcataract operations in national blindness control program is done by - \nSelect and explain. \nA. Active surveillance, B. Passive surveillance, C. Sentinel surveillance, D. Routine check-up', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Sentinel surveillance o 25 sentinel surveillance units have been established in depaments of ophthalmology and PSM in medical collages in India for assessment of - Beneficiary profiles. Visual outcomes based on cataract surgery records. Follow-up of operated cases. Ocular morbity data.", 'role': 'assistant'}]