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': 'All of the following may be used to differentiate central retinal venous occlusion (CRVO) from ocular ischemic syndrome due to carotidaery stenosis, except: \nSelect and explain. \nA. Dilated retinal vein, B. Touous retinal vein, C. Retinal aery pressure, D. Ophthalmodynamometry', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Dilated retinal vein', 'role': 'assistant'}]