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: Social & Preventive Medicine
[{'content': 'Auditory fatigue occurs at- Hz - \nSelect and explain. \nA. 2000, B. 3000, C. 4000, D. 8000', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., 4000 Hz", 'role': 'assistant'}]