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
Deforming Polyarthritis is associated with all of the following except - 
Select and explain. 
A. Rheumatoid arthritis, B. Psoriatic arthritis, C. Behcet's syndrome, D. Ankylosing spondylitis
C: Behcet's syndrome
Answer: C: Behcet's syndrome 
Explanation: The arthritis of Bechet's syndrome is not deforming and affects knees and ankles.
Rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, neuropathic arthropathy etc. cause deforming arthritis.