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': 'Spontaneous vertical nystagmus is seen in the lesion of \nSelect and explain. \nA. Midbrain, B. Labyrinth, C. Vestibule, D. Cochlea', 'role': 'user'}, {'content': 'Answer: A \nExplanation: “Vertical nystagmus means vertical displacement of the eye, not side to side nystagmus when attempting upward or down ward gaze. As defined vertical nystagmus always indicates brainstem dysfunction”', 'role': 'assistant'}]