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': 'Central mystagmus ? \nSelect and explain. \nA. Suppressed by optic fixation, B. More than 1 minute duration, C. Fixed direction, D. Fatiguable', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is `b' i.e., More than 1 minute duration", 'role': 'assistant'}]