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: Anatomy
[{'content': 'Which of the following is an example of saddle joint \nSelect and explain. \nA. Carpo-metacarpal joint of the thumb, B. Carpo-metacarpal joint of the thumb, C. Ankle joint, D. Knee joint', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Carpometacarpal joint of thumb', 'role': 'assistant'}]