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 at macula is seen in all of the following except: \nSelect and explain. \nA. Tay-Sach's disease, B. Letterer-Siwe disease, C. Niemann-Pick disease, D. Commotio retinae", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Letterer-Siwe disease', 'role': 'assistant'}]