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: Social & Preventive Medicine
Area between one standard detion on either side of mean in normal distribution curve is - 
Select and explain. 
A. 62%, B. 68%, C. 90%, D. 99%
B: 68%
Answer: B: 68% 
Explanation: Ans. is 'b' i.e., 68%