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: Social & Preventive Medicine
[{'content': 'The following statistic is used to measure the linear association between two characteristics in the same individuals - \nSelect and explain. \nA. Coefficient of variation, B. Coefficient of correlation, C. Chi square, D. Standard error', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]