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: Orthopaedics
[{'content': "Jefferson's fracture is - \nSelect and explain. \nA. C1, B. C2, C. C2 C1, D. C2C3", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]