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': 'Cause of U/L secretory otitis media in an adult is - \nSelect and explain. \nA. CSOM, B. Nasopharyngeal carcinoma, C. Mastoiditis, D. Foreign body of external ear', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Unilateral serous otitis media in an adult should always raise the suspicion of a benign / malignant tumor of nasopharynx\n“In adults presenting with a unilateral middle ear effusion the possibility of a nasopharyngeal carcinoma should be considered”.\nRef. Dhingra 5/e, p 72, 6/e, p 251; Current Laryngology 2/e, p 659', 'role': 'assistant'}]