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': 'First flouride varnish discovered in Europe has what percentage of NaF \nSelect and explain. \nA. 2.26%, B. 5%, C. 8%, D. 10%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]