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': 'A young adult presents with proptosis and pain in eye after 4 days of trauma to eye. Chemosis, conjunctival congestion and extraocular muscle palsy with inability to move eye are seen.Investigation of choice - \nSelect and explain. \nA. MRI, B. Digital subtraction angiography, C. CT, D. MR angiography', 'role': 'user'}, {'content': "Answer: B \nExplanation: Information in this question are :-\n\n\nPresentation 4 days after trauma\nTraumatic proptosis along with chemosis and conjunctival congestion\nExtraocular muscle palsy (ophthalmoplegia)\n\n\nGiven the patient's clinical presentation of proptosis with chemosis and conjunctival congestion in the setting of cranio-facial injury, a traumatic carotid-cavernous fistula is suspected.\nMost likely diagnosis is carotico-cavernous fistula.\nSelective carotid angiography using digital subtraction techniques is the investigation of choice.\nAnother condition which may present with similar features is CST, but it is very rare after trauma.", 'role': 'assistant'}]