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
95% of confidence limit exist between - 
Select and explain. 
A. +- 1. S.D., B. +-2 S.D., C. +-3 S.D, D. +- 4 S.D.
B: +-2 S.D.
Answer: B: +-2 S.D. 
Explanation: Ans. is 'b' i.e., +- 2 SD 1 SD --> Coveres 68% of area (68% confidence limit) 2 SD --4 Coveres 95% of area (95% confidence limit) 3 SD --> Coveres 99.7% of area (99.7% confidence limit)