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': 'Tom Smith arthritis involves - \nSelect and explain. \nA. Knee, B. Hip, C. Ankle, D. Wrist', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]