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
Correlation coefficient of 0.5 indicates 
Select and explain. 
A. Confidence interval of 95 %, B. Weak association, C. Not statistically significant, D. Good association
B: Weak association
Answer: B: Weak association 
Explanation: Ref:Park's Textbook of Preventive and Social Medicine 25th Ed