The graph below shows a line of best fit for data collected on the amount of time students spent studying in relation to their score on a test. The equation of the line of best fit is y = 10x + 40. What does the y-intercept represent? A. the total number of hours the students spent studying B. the test score of a student who did not study C. the average number of hours the students spent studying D. the total number of questions on the test