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': 'Otosclerosis mostly affects: \nSelect and explain. \nA. Malleus, B. Stapes, C. Incus, D. Tympanic membrane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Otosclerosis is caused by immobility of the stapes. Its most distinctive feature is conductive hearing loss, but sensorineural hearing loss and veigo are also common; tinnitus is infrequent. Otosclerosis is suggested by a positive family history, a tendency toward onset at an earlier age, the presence of conductive hearing loss, or bilateral symmetric auditory impairment Treatment with a combination of sodium fluoride, calcium gluconate, and vitamin D may be effective. If not, surgical stapedectomy should be considered.', 'role': 'assistant'}]