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
Number of vision centers under vision 2020, a national program for control of blindness are - 
Select and explain. 
A. 20, B. 200, C. 2000, D. 20000
D: 20000
Answer: D: 20000 
Explanation: Ans. is 'd' i.e., 20000 The proposed structure for vision 2020, NPCB : Vision centres 20,000 (Primary level)Service centres 2,000 (Secondary level)Tranning centres 200 (Teiary level)Centres of Excellence 20 (COE)