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
Most common detion used in social medicine is 
Select and explain. 
A. Mean, B. Range, C. Variance, D. Standard detion
D: Standard detion
Answer: D: Standard detion 
Explanation: The standard detion : Most frequently used measure of detion Defined as "Root -Means -Square -Detion " Ref : Park&;s Textbook of Preventive and Social Medicine; 23rd edition - Pgno. 848