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': 'According to WHO classification, for severe degree of impairment of hearing is at - \nSelect and explain. \nA. 26 - 40 dB, B. 41-55 dB, C. 56-70 dB, D. 71-91 dB', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]