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': 'Number of centre of excellence in vision 2020 – \nSelect and explain. \nA. 20, B. 200, C. 2000, D. 20000', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]