This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Standard deviation to mean ratio denotes the \nSelect and explain. \nA. Standard error, B. Coefficient of variance, C. Proportion, D. Coefficient of skewness', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]