This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
[{'content': 'A young man following A presented with proptosis and pain in right eye after four days. On examination there is bruise on forehead and right eye. What is the diagnosis - \nSelect and explain. \nA. Cavernous sinus thrombosis, B. Internal carotid aery aneurysm, C. Carotico-cavernous fistula, D. Fracture of sphenoid', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Carotid cavernous fistula is an acquired abnormal communication between the carotid aerial system and the venous cavernous sinus . Conjuctival congestion and chemosis is the differentiating feature. Ref : ak khurana 6th edition pg no 416', 'role': 'assistant'}]