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: Ophthalmology
[{'content': 'Down beat nystagmus is seen in? \nSelect and explain. \nA. Arnold chiari malformation, B. Brain stem damage, C. Pontine hemorrhage, D. Labyrinthine damage', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Arnold chiari malformation Down-beat nystagmus are seen in cerebellar lesion and Arnold-chiary malformation", 'role': 'assistant'}]