Suppose the Cost of Operating a 75-Room Hotel for a Night

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 average benefit will exceed the marginal cost.
B) more than $40; 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 $80; because the marginal benefit will exceed the marginal cost.