The Speedy Jet Ski Rental Company charges an insurance fee and an hourly rental rate. The total cost is modeled by the function R(x) 5 30 1 40x. Based on this model, which statements are true?

I. R(x) represents the total cost.
II. x is the number of hours rented. $40 is the III. insurance fee.
IV. $30 is the hourly rental rate.

(1) I, only
(2) I and II, only
(3) I, III, and IV, only
(4) I, II, III, and IV