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: Medicine
[{'content': 'Sea saw nystagmus is seen in - \nSelect and explain. \nA. Anterior longitudinal fasiculus, B. Craniopharyngioma, C. Medullary lesion, D. GB. Syndrome', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]