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': 'Which of the following site is least commonly involved in ahrogryposis ? \nSelect and explain. \nA. Knee, B. Hip, C. Trunk, D. Elbow', 'role': 'user'}, {'content': 'Answer: C \nExplanation: . ref : maheswari 9thed essentials of pediatric ohopedics 5th ed', 'role': 'assistant'}]