The cost, in dollars, of parking a car in a busy downtown area for h hours is $10 + $3h. Which statement is correct?
A.
For every hour the car is parked, the cost increases by $10.

B.
For every hour the car is parked, the cost increases by $7.

C.
For every hour the car is parked, the cost increases by $13.

D.
For every hour the car is parked, the cost increases by $3.