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': 'Treatment for idiopathic bone cavity is : \nSelect and explain. \nA. Opening and induce bleeding by scraping, B. Marsupialization, C. Enucleation, D. No treatment is required', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]