Allie's Car Needs an Oil Change

Allie's car needs an oil change. She can take the car to an auto shop and have the oil changed for $35 or she can change the oil herself for $10. If Allie changes the oil herself, she will have to take two hours off from her job where she earns $15 per hour. Which of the following statements is true?

A) Allie should change the oil herself, because $10 is cheaper than $35.
B) The opportunity cost of changing the oil herself is $30.
C) Allie should change the oil herself, because the opportunity cost of changing it is only $30.
D) The opportunity cost of changing the oil herself is $40.