This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'In noise-induced hearing loss, audiogram shows a typical notch at \nSelect and explain. \nA. 1000 Hz, B. 2000 Hz, C. 3000 Hz, D. 4000 Hz', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Audiogram in NIHL shows a typical notch at 4000kHz, for both air and bone conduction. (Ref: Diseases of EAR, NOSE AND THROAT by PL DHINGRA - 6th Edition)', 'role': 'assistant'}]