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 center of excellance in vision 2020 - 
Select and explain. 
A. 20, B. 200, C. 2000, D. 20000
A: 20
Answer: A: 20 
Explanation: Ans. is 'a' i.e., 20