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': 'Among the following varnish Which of the following has flouride concentration less than duraphat but having equivalent efficacy: \nSelect and explain. \nA. Duraflour, B. Carex, C. Flour protector., D. None of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Flouride varnish was first developed in Europe by Schimdt. They maintain the fluoride ions in intimate contact with enamel for longer periods. The two commonly used varnishes are –\n\nDuraphat: It is the first flouride varnish and contains 22600 ppm fluoride as NaF in a neutral colophonium base (NaF varnish containing 2.26% fluoride in organic lacquer)\nFluor Protector (Fluoride concentration is about 7000 ppm or 0.70%)\nCarex: Contains a lower fluoride concentration than Duraphat--(1.8% \xa0fluoride) and has efficacy equivalent to that of Duraphat.\nDuraflour - 22.6 mg/ml.\n\nContains NaF in alcoholic suspension of natural resins with xylitol as sweetening agent.\n\nCavity shield: 5% NaF in resinous base.', 'role': 'assistant'}]