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': 'Pencil in cup deformity is seen in: \nSelect and explain. \nA. Rheumatoid ahritis, B. Ankylosing spondylitis, C. Gout, D. Psoriatic ahritis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Pencil-in-cup deformity--psoriasis Asymmetric oligoahritis is themost common presentationin psoriatic ahritis', 'role': 'assistant'}]