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
The screening strategy for prevention of blindness from diabetic retinopathy according to the NPCB involves- 
Select and explain. 
A. Oppounistic screening, B. High risk screening, C. Mass screening, D. Screening by primary care physician
B: High risk screening
Answer: B: High risk screening 
Explanation: 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.