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': "Not a Radiological feature of x-ray \nSelect and explain. \nA. Wimberger's sign, B. Frankel's line, C. Subperiosteal hemorrhage, D. Ivory vertebrae", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]