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
Not a Radiological feature of x-ray 
Select and explain. 
A. Wimberger's sign, B. Frankel's line, C. Subperiosteal hemorrhage, D. Ivory vertebrae
D: Ivory vertebrae
Answer: D: Ivory vertebrae 
Explanation: None