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': 'Kiel bone is:\nXenograft\nAllograft\nTreated by detergent, sterilized and freeze dried.\nOx or calf bone denatured with 20% H2O2, acetone and sterilized. \nSelect and explain. \nA. 1&3, B. 2&3, C. 1&4, D. 2&4', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]