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
[{'content': 'If one wants to compare in two characteristics with variable differencr, which measurement should be used? \nSelect and explain. \nA. Standard detion, B. Percentile, C. Variance, D. Co-efficient variation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .', 'role': 'assistant'}]