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': "Cherry red spot on retina is seen in A/E \nSelect and explain. \nA. CRAO, B. CRVO, C. Nieman-pick diseases, D. Tay-sach's disease", 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. CRVO', 'role': 'assistant'}]