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: Surgery
Distal interphalangeal joints are involved in all except ? 
Select and explain. 
A. Psoriatic ahritis, B. Rheumatoid ahritis, C. Reactive ahritis, D. Osteoahritis
B: Rheumatoid ahritis
Answer: B: Rheumatoid ahritis 
Explanation: Ans. is 'b' i.e., Rheumatoid ahritis