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: Ans. Digital subtraction angiography', 'role': 'assistant'}]