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
Which is a hinge joint : 
Select and explain. 
A. Knee, B. Elbow, C. Metacarpophalangeal, D. Atlanto Axial
B: Elbow
Answer: B: Elbow 
Explanation: B i.e. Elbow