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': 'A pregnant woman in third trimester complains of hearing her own sounds. Examination of the ear shows movements of tympanic membrane synchronous with respiration and especially exaggerated when nostril on the contralateral side is occluded. Your diagnosis is: \nSelect and explain. \nA. Eustachian tube obstruction, B. Patulous eustachian tube, C. Otitis media with effusion, D. Otosclerosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Patulous eustachian tube is an abnormally patent tube seen in the third trimester of pregnancy or in rapid weight loss. Symptoms complained by her are due to autophony. Conductive hearing loss due to otosclerosis, otitis media with effusion and retracted tympanic membrane also conduct body sounds to the ear but her tympanic membrane findings of movement with respiration are typically seen in patulous eustachian tube.', 'role': 'assistant'}]