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': 'Restoration margins are plaque-retentive and produce the most inflammation when they are located \nSelect and explain. \nA. Supragingival, B. Subgingival, C. At the level of the gingival margin, D. On buccal surfaces of teeth', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Supragingival margins are least detrimental to the gingival tissues; subgingival margins are the most detrimental due to the accumulation of dental plaque.', 'role': 'assistant'}]