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': 'Cause of unilateral 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: Benign and malignant tumours of nasopharynx should always be excluded in unilateral serous otitis media in an adult. Nasopharyngeal carcinoma Clinical features Nasal: Nasal obstruction, nasal discharge, denasal speech and epistaxis. Otalgic: Due to obstruction of the eustachian tube, there is a conductive type of hearing loss, serous or suppoive otitis media. Tinnitus and dizziness may occur. Presence of unilateral serous otitis media in an adult should raise suspicion of nasopharyngeal growth. Ophthalmoneurologic: Squint and Diplopia(CN 6), Ophthalmoplegia( CN 3,4 and 6) facial pain and reduction of corneal reflex(CN 5), exophthalmos and blindness(CN 2).Involvement of CN 9,10,11 may occur constituting jugular foramen syndrome. Involvement of the cervical sympathetic chain causes horner's syndrome. Cervical nodal metastasis. (Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 284,285)", 'role': 'assistant'}]