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': 'B-type tympanogram is seen in- \nSelect and explain. \nA. Serous otitis media, B. Ossicular discontinuity, C. Otosclerosis, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]