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': 'Decreased bone conduction in an audiogram indicates: \nSelect and explain. \nA. Tympanic membrane perforation, B. Ossicular dislocation, C. Ossicular fixation, D. Damage to cochlea', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Bone conduction is a measure of cochlear function. This is tested either by Schwabach test or absolute bone conduction test or audiometrically by placing the vibrator on the mastoid bone. Decreased bone conduction or loss of it indicates hypoactive or non-functioning cochlea. All other conditions listed in (a), (b) and (c) cause conductive hearing loss with cochlear function remaining normal.', 'role': 'assistant'}]