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
Apicectomy is: 
Select and explain. 
A. Periapical curettage, B. Retrograde restoration, C. Surgical removal of root, D. Surgical removal of root tip of an endodontically treated tooth
D: Surgical removal of root tip of an endodontically treated tooth
Answer: D: Surgical removal of root tip of an endodontically treated tooth 
Explanation: None