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: Radiology
[{'content': 'Investigation of choice for Aoic Dissection is \nSelect and explain. \nA. Aoography, B. CT scan, C. MRI, D. X-Ray chest', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. MRI', 'role': 'assistant'}]