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': 'A 6 year old boy presents with painful limp. On clinical examination, tenderness in femoral triangle and some limitation of Hip movements. X-ray is normal, Next investigation \nSelect and explain. \nA. MRI, B. CT scan, C. Arthroscopy, D. Bone scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]