If 9 pizzas cost $67.50 that means that 1 pizza costs 67.50/9 = $7.5
Answer A is incorrect because of false prize of pizza.
B isn't correct because 1 pizza cost $7,5 and not 7,5 pizzas cost $1
C isn't answer because of both reasons from answer A and answer B
D is the answer because it says that you need to pay $7.5 per pizza.