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': 'Which of the following is a major contraindication to \nresection of crestal bone? \nSelect and explain. \nA. Gingival recession, B. Post surgical infection, C. Removal of healthy bone, D. Weakening', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]