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
Decalcified freeze-dried bone graft is an example of 
Select and explain. 
A. Xenograft, B. Autograft, C. Alloplast, D. Allograft
D: Allograft
Answer: D: Allograft 
Explanation: None