This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnostic & Operative ENT, Subject name: ENT
[{'content': "The following test is useful for diagnosis of \nSelect and explain. \nA. Unsafe CSOM, B. Meniere's disease, C. Gradenigo syndrome, D. Cholesteatoma", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) Meniere's disease.* The image shows performance of the caloric stimulation test.* Irrigation of the external meatus with water 7deg above and later 7deg below body temperature sets up convection currents of the endolymph in the semi-circular canals.* This causes nystagmus, and the duration of the nystagmus gives an index of the activity of the labyrinth. The nystagmus can be directly observed or recorded electrically (electronystagmography).* This test is particularly valuable in the diagnosis of Meniere's disease and acoustic neuroma. A reduced or absent nystagmus is found (canal paresis).", 'role': 'assistant'}]