Each month, Nadeem keeps track of the number of times he visits the library and the number of books he checks out. Is there a correlation if you model his data with a linear equation? Is there a causal relationship?

A. There is a positive correlation and no causal relationship.
B. There is a negative correlation and no casual relationship.
C. There is a casual relationship but no positive correlation.
D. There is neither a correlation nor a casual relationship.