The correlation coefficient $r = 0.91$ indicates a strong positive linear association between the two variables. Since the value of $r$ is close to 1, this suggests a strong relationship, and because it's positive, the association is positive.

Thus, the correct interpretation is:

D. There is a strong positive linear association between the two variables.

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Related Questions:

1. What is the range of possible values for the correlation coefficient $r$?
2. How do you interpret negative correlation coefficients?
3. What does a correlation coefficient of 0 signify?
4. Can a correlation coefficient indicate causality between variables?
5. How would you calculate the correlation coefficient from a dataset?

Tip:

A correlation coefficient close to 1 or -1 indicates a strong relationship, while a value close to 0 indicates little to no linear relationship.