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
Which is not involved in Ankylosing spondylitis - 
Select and explain. 
A. Knee & Ankle, B. Sacroilac Jt., C. Wrist & elbow, D. Spine
C: Wrist & elbow
Answer: C: Wrist & elbow 
Explanation: Joints involvement in AS
Sacroiliac > spine & costovertebral > Hip > shoulder > knee > ankle