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
Which of the following substances is filled in the bone cavity after enucleation of a cyst: 
Select and explain. 
A. Hydroxyapatite, B. Autogenous cortical bone chips, C. Autogenous medullary bone chips, D. Allogenic bone chips
C: Autogenous medullary bone chips
Answer: C: Autogenous medullary bone chips 
Explanation: None