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
The mean DMFT values for 12 year old school children is 2.5. 68% of the population has DMFT values between 2
and 3. The standard deviation for the population is: 
Select and explain. 
A. 0.5, B. 1, C. 2, D. 3
A: 0.5
Answer: A: 0.5 
Explanation: None