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': 'Following are seen in CRA occlusion except: \nSelect and explain. \nA. Gradual loss of vision, B. Headache, C. Sudden loss of vision, D. Retained central vision', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Gradual loss of vision', 'role': 'assistant'}]