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': '50 year old man with dashboard injury in RTA. Dislocation was reduced after 3 days, started complaining of pain in left hip after 6 months x-ray pelvis is normal. most relevant investigation \nSelect and explain. \nA. MRI, B. USG, C. CT, D. HR - CT', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]