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 is a hinge joint : \nSelect and explain. \nA. Knee, B. Elbow, C. Metacarpophalangeal, D. Atlanto Axial', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Elbow', 'role': 'assistant'}]