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
If one wants to compare in two characteristics with variable differencr, which measurement should be used? 
Select and explain. 
A. Standard detion, B. Percentile, C. Variance, D. Co-efficient variation
D: Co-efficient variation
Answer: D: Co-efficient variation 
Explanation: .