Periodic tune-ups are important because they
a. extend the life of your car
b. you avoid costly repairs
c. prevent dangerous breakdowns
d. all of the above

Periodic tune-ups are important because they D. all of the above. They can definitely extend the life of your car, because if you fix something even before it is broken, you won't have to think about that for a long time. It can help you avoid costly repairs because you will usually have just small repairs since you won't give your car the time to get broken. It can also prevent dangerous breakdowns if you regularly drive your car for a check-up.