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: Orthopaedics
[{'content': "Investigation of choice for perthe's disease \nSelect and explain. \nA. TC 99 scan, B. MRI, C. CT Scan, D. X-ray", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]