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': 'External auditory canal exostosis occurs due to \nSelect and explain. \nA. Repeated instrumentation, B. Recurrent otitis externa, C. Wide external auditory meatus, D. Recurrent prolonged cold water exposure', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Exostoses are multiple and bilateral, often presenting as smooth, sessile, bony swellings in the deeper pa of the meatus near the tympanic membrane.They often arise from the compact bone. Exostoses is often seen in persons exposed to the entry of cold water in the meatus as in swimmers and divers. Reference: Diseases of Ear, Nose and Throat, PL Dhingra, 7th edition, pg no. 118', 'role': 'assistant'}]