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': 'For satisfactory vision t he minimum illumination accepted is - \nSelect and explain. \nA. 15 to 20 foot candles, B. 30 to 40 candles, C. 40 to 50 candles, D. 70 to 90 candles', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 15 to 20 foot candles", 'role': 'assistant'}]