This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
The measure of variability indicating how many standard detions, an observation is above or below the mean is 
Select and explain. 
A. Z score, B. Standard error (S.E), C. Standard detion (S.D), D. Co-efficient of Variation
A: Z score
Answer: A: Z score 
Explanation: A z-score is the number of standard detions from the mean. The coefficient of variation (CV) is a measure of relative variability. It is the ratio of the standard detion to the mean. Ref : Park 23rd edition Pgno : 849