The graph below shows a line of best fit for data collected on the amount customers spent on a file sharing service in relation to the amount they uploaded. The equation of the line of best fit is shown below.

Y = 10/9x + 5

What does the y-intercept represent?
A.
the cost to enroll in the file sharing service

B.
the cost per file uploaded

C.
the cost to upload an unlimited amount of files

D.
the cost per Mb uploaded