Twelve college seniors were chosen at random and surveyed. The survey asked the participants for the number of hours they spent studying per week and their overall GPA. Letting X represent the number of hours a student spent studying and Y represent a student's overall GPA, the surveyor calculated the correlation coefficient between X and Y to be 0.85. Interpret the correlation coefficient calculated by choosing the statement below which correctly describes the correlation between X and Y.

A. weak positive correlation
B. weak negative correlation
C. strong positive correlation
D. no correlation