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
Water fluoride concentration in areas with cold weather condition 
Select and explain. 
A. More than 1 ppm, B. 1 ppm, C. Less than 0.7 ppm, D. 4 ppm
A: More than 1 ppm
Answer: A: More than 1 ppm 
Explanation: None