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': 'Maintenance of oral health is best achieved by \nSelect and explain. \nA. hard bristle tooth brush, B. Mouth wash, C. A soft bristle brush and tooth paste, D. A soft bristle brush and dental floss', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]