This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint disorders, Subject name: Orthopaedics
[{'content': 'Ahritis involving DIP, PIP, 1st carpometacarpal with sparing of MCP and wrist joints is typical of: \nSelect and explain. \nA. Osteoahritis, B. Rheumatoid ahritis, C. Ankylosing spondylitis, D. Psoriatic ahritis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Osteoahritis characteristically involves distal interphalangeal joint (Heberden's node), proximal interphalangeal joint (Bouchard's node), 1st carpometacarpal joint (base of thumb) of hand with sparing of metacarpophalangeal joint and wrist joint. Fig. Joints involved in osteoahritis", 'role': 'assistant'}]