This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Orthopaedics
[{'content': 'Swan neck deformity is seen in \nSelect and explain. \nA. Osteoahritis, B. Rheumatoid ahritis, C. Psoriatic ahritis, D. Gout', 'role': 'user'}, {'content': "Answer: B \nExplanation: Impoant deformities of hand in RABoutonniere deformity: flexion contracture of PIP joint and extension of DIP jointSwan neck deformity: Hyperextension of PIP joint and flexion at DIP jointZ-deformity: radial detion of the wrist with ulnar detion of fingersHyperextension of 1st interphalangeal joint and flexion on MP joint(Refer: Mohindra's Fundamentals of Ohopedics, 2nd edition, pg no. 420)", 'role': 'assistant'}]