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': 'Apicectomy is: \nSelect and explain. \nA. Periapical curettage, B. Retrograde restoration, C. Surgical removal of root, D. Surgical removal of root tip of an endodontically treated tooth', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]