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: Medicine
[{'content': "Features of carotid-cavernous fistula include - \nSelect and explain. \nA. Dilated superior ophthalmic vein on CT scan, B. Blood in the Schlemm's canal, C. Proptosis of contralateral eye suggests bilateral carotid-cavernous fistula, D. Traumatic fistula rarely close spontaneously", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]