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: Surgery
[{'content': 'Radiographic finding of floating teeth can be seen in - \nSelect and explain. \nA. Ectodermal dysplasis, B. Cleido cranial dysplasia, C. Osteopetrosis, D. Histiocytosis - X', 'role': 'user'}, {'content': 'Answer: D \nExplanation: On radiographic examination of mandible, erosion of the bony alveoli around the teeth, so that they seem to be floating in space.\nSeen in histiocytosis X.', 'role': 'assistant'}]