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': 'Which of the following substances is filled in the bone cavity after enucleation of a cyst: \nSelect and explain. \nA. Hydroxyapatite, B. Autogenous cortical bone chips, C. Autogenous medullary bone chips, D. Allogenic bone chips', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]