This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Health education & planning, Subject name: Social & Preventive Medicine
[{'content': 'Acceptable noise level in hospital wards \nSelect and explain. \nA. 20 - 35dB, B. 35 - 40 dB, C. 45-55dB, D. 50-60dB', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ref:Park's Textbook of Preventive and Social Medicine 25th Ed", 'role': 'assistant'}]