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': 'Keratosis obturans is \nSelect and explain. \nA. Foreign body in external auditory canal, B. Desquamated epithelial cells and Cholesterol, C. Cholesterol crystals surrounded by calcium, D. Wax in external auditory canal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Keratosis obturans is a collection of the pearly white mass of desquamated epithelial cells in the deep meatus. This, by its pressure effect, causes absorption of bone leading to widening of the meatus so much so that facial nerve may be exposed and paralyzed. Presenting symptoms may be a pain in the ear, hearing loss, tinnitus and sometimes ear discharge. (Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 58)', 'role': 'assistant'}]