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': "Carha's notch in an audiogram represent which of the following deepest frequency? \nSelect and explain. \nA. 0.5 KHz, B. 2 KHz, C. 4 KHz, D. 8 KHz", 'role': 'user'}, {'content': "Answer: B \nExplanation: Carha's notch is seen in patients with otosclerosis. It is a dip in the bone conduction curve seen maximally at 2 KHz region. It disappears after successful stapedectomy.", 'role': 'assistant'}]