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
Concentration of fluoride in community water supplies as proposed by WHO in 1969 was- 
Select and explain. 
A. 1.5 ppm, B. 1 ppm, C. 0.5 ppm, D. 2 ppm
B: 1 ppm
Answer: B: 1 ppm 
Explanation: In 1969, WHO advocated that 1 ppm of fluoride in community water supplies was a practical and effective public health measure.