This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
[{'content': 'The screening strategy for prevention of blindness from diabetic retinopathy according to the NPCB involves- \nSelect and explain. \nA. Oppounistic screening, B. High risk screening, C. Mass screening, D. Screening by primary care physician', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: Parks 23rd edition pg 137 Screening will be most productive if applied selectively to high-risk groups, the groups defined on the basis of epidemiological research.', 'role': 'assistant'}]