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
All of the following may be used to differentiate central retinal venous occlusion (CRVO) from ocular ischemic syndrome due to carotidaery stenosis, except: 
Select and explain. 
A. Dilated retinal vein, B. Touous retinal vein, C. Retinal aery pressure, D. Ophthalmodynamometry
A: Dilated retinal vein
Answer: A: Dilated retinal vein 
Explanation: Ans. Dilated retinal vein