The cost, in dollars, of parking a car in a busy downtown area for h hours is $15 + $5h. 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 $5. C. For every hour the car is parked, the cost increases by $20. D. For every hour the car is parked, the cost increases by $15.