Jack works after school. Each day he is paid a set amount, plus an hourly wage. Look at the table. Choose the linear function f Jack can use to find his pay.

Hours 1 1.5 2 2.5 3
Pay 18 23 28 33 38
A. f(x) = 10x + 8
B. f(x) = 15x + 3
C. f(x) = 0.5x + 1
D. f(x) = x + 18