Ben conducted an experiment to determine the association between the number of hours spent studying per day with GPA. The line of best fit for his data has a slope of 1, with time, in hours, as the independent variable x and GPA as the dependent variable, y. What does a slope of 1 mean in this context?
A) GPA is 1 point every hour.
B) GPA of 1 point is at zero hours.
C) GPA increases by 1 additional point per hour.
D) Time decreases by 1 hour for every GPA point increase.