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': 'Stannous fluoride concentration used in topical fluoride is: \nSelect and explain. \nA. 8%, B. 2%, C. 1.23%, D. 12%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Stannous fluoride has been used at 8% and 10% concentrations in solutions equivalent to 2 and 2.5% fluoride. Although the 10% solution is usually used for adults and 8% for children, there is no evidence of an actual clinical difference between the two. However, the most commonly used is 8% stannous fluoride preparation.\nEssentials of preventive and community dentistry\xa0\nSoben Peter\xa0\n5th edition', 'role': 'assistant'}]