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: Dental
The best way to fill a bony defect will be with which of the following? 
Select and explain. 
A. Hydroxy apatite, B. Donor graft, C. Xenograft, D. Autograft
D: Autograft
Answer: D: Autograft 
Explanation: None