This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal system, Subject name: Anatomy
Which of the following is true about psoriatic ahritis 
Select and explain. 
A. Involves distal joints of hand and foot, B. Pencil in cup deformity, C. Sacroiliitis, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Reference Robbins page no Pg 8th 1241