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': 'Keratosis obturans is - \nSelect and explain. \nA. Foreign body in external auditory canal, B. Desquamated epithelial cell + Cholesterol, C. Cholesterol crystals surrounded by calcium, D. Wax in external auditory canal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]