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': 'Auditory fatigue is seen at \nSelect and explain. \nA. 90 dB, 4000Hz, B. 110 dB, 4000Hz, C. 130 dB, 4000Hz, D. 150 dB, 4000Hz', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Auditory fatigue occurs at 90dB, 4000Hz. 90dB for 8hour a day for 5weeks is the maximum safe limit. (Ref: Diseases of EAR, NOSE AND THROAT by PL DHINGRA - 6th Edition)', 'role': 'assistant'}]