This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
Area under normal curve within +- 1SD (standard detion)- 
Select and explain. 
A. 0.68, B. 0.17, C. 0.12, D. 0.34
A: 0.68
Answer: A: 0.68 
Explanation: Ref:Parks 23rd edition pg 849. +/-1sd includes 68% i.e . 0.68 1SD : confidence limit = 68% 2SD : confidence limit = 95% 3SD : confidence limit = 99.7%