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
All of the following joints ossify 16 years of age except 
Select and explain. 
A. Ankle, B. Hip, C. Knee, D. Elbow
C: Knee
Answer: C: Knee 
Explanation: Milking Position, to remember age of ossification of skeletal maturity.

Joints facing toward sky like shoulder, wrist and knee ossify around 18 years.
Joints facing towards ground like hip, ankle and elbow ossify around 16 years.