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': "Cause of cherry red spot \nSelect and explain. \nA. CRVO, B. Berlin's odema, C. Eales disease, D. All of the above", 'role': 'user'}, {'content': "Answer: B \nExplanation: Most important cause is trauma (Berlin's odema).", 'role': 'assistant'}]