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': 'When scaling and root planning, the primary objective of the procedure is to \nSelect and explain. \nA. Cause shrinkage of gingival tissue, B. Create glass - like root surfaces, C. Remove all cementum, D. Restore the gingival tissue to health', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]