This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: ENT
Carha's notch in audiometry is seen in: 
Select and explain. 
A. Ossicular discontinuity, B. Hemotypanum, C. Otomycosis, D. Otosclerosis
D: Otosclerosis
Answer: D: Otosclerosis 
Explanation: TheCarha notchis a depression in the bone-conduction audiogram of patients with clinical otosclerosis. It is different at different frequencies but maximum at 2000hz and it called Carha notch. which correspond to the resonance frequency of the middle ear, can be substantially improved following successful stapes surgery.