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': 'Gingival finish lines are placed \nSelect and explain. \nA. Supra/subgingivally according to need, B. For better cleansing, C. Subgingivally only, D. Supragingivally only', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]