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
[{'content': 'Distal interphalangeal joints are involved in all except ? \nSelect and explain. \nA. Psoriatic ahritis, B. Rheumatoid ahritis, C. Reactive ahritis, D. Osteoahritis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Rheumatoid ahritis", 'role': 'assistant'}]