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: Medicine
[{'content': 'Least common site to involved in osteoarthritis amongst the following is - \nSelect and explain. \nA. Hip joint, B. Knee joint, C. Carpometacarpal joint of thumb, D. Metacarpophalangeal joint', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]