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
[{'content': 'Bone blending is a technique employed for \nSelect and explain. \nA. Transplanting cortical bone, B. Transplanting cancellous bone, C. Transplanting a mix of cancellous bone and hydroxyapatite crystals, D. Transplanting resorbable hydroxyapatite crystals only', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]