Suppose the cost of operating a 75-room hotel for a night is $6,000 and there are five empty rooms for tonight. If the marginal cost of operating one room for one night is $40, the hotel manager should rent one of the empty rooms only if a customer is willing to pay a. more than $40; because the marginal benefit will exceed the marginal cost. b. more than $80; because the marginal benefit will exceed the marginal cost. c. more than $80; because the average benefit will exceed the marginal cost. d. more than $40; because the average benefit will exceed the marginal cost.