This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal system, Subject name: Radiology
[{'content': 'Floating teeth sign is seen in \nSelect and explain. \nA. Metastasis, B. Osteitis fibrosa, C. Histiocytosis, D. Asbestosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Radiological features of Langerhans cell histiocytosis : Punched out lytic lesions of skull with bevelled edges. Geographic skull. Floating teeth sign due to radiolucent lesion around the teeth. Veebra plana', 'role': 'assistant'}]