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': 'Floating tooth sign is seen in: \nSelect and explain. \nA. Dentigerous cyst, B. Periapical cyst, C. Aphthous ulcers, D. Histiocytosis x', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Floating tooth sign is seen with Histiocytosis x, because of erosion of bonyalveoli around the teeth.', 'role': 'assistant'}]