A parking lot charges $2 per hour for the first 4 hours, then $3 per hour after that. Which equation(s) describes the total cost as a function of the hours x?
A. Y=3x+8
B. Y=2x+12
C. Y=2x for x of 4 or less / y=2x+3x for x of 5 or more
D. Y=2x for x of 4 or less / y=8x+3(x-4) for x of 5 or more