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': 'Effective use of dental floss can be expected to: \nSelect and explain. \nA. Significantly reduce caries activity, B. Improve gingival health, C. Restrict plaque development, D. Effectively alter the oral environment', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]