A linear graph models the relationship between the number of pages printed, , and the total cost, , in dollars, for a printing service. The service charges a setup fee plus a cost per page. If the equation of the line is , which of the following is the best interpretation of the slope of the graph? 
The total cost for 10 pages.
The setup fee for the printing service.
The cost per page, in dollars.
The number of pages printed for
