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: ENT
[{'content': 'Voice induced impairment of hearing at - \nSelect and explain. \nA. 1000Hz, B. 2000 Hz, C. 3000Hz, D. 4000 Hz', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]