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': "Brown's sign is seen In \nSelect and explain. \nA. Glomus tumour, B. Meniere's disease, C. Acoustic neuroma, D. Otosclerosis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Brown's sign, also called pulsation sign, is seen in glomus tumour. When pressure is raised in the ear canal with a Siegel's speculum, tumour first pulsates vigorously and then blanches; reverse occurs when pressure is released.", 'role': 'assistant'}]