Rex Carr Could Pay $10 for a Shovel That Lasts

Rex Carr could pay $10 for a shovel that lasts one year and pay $5 a car to his brother Scoop to bury the cars, or he could buy a low-quality car smasher that costs $200 a year to own and that smashes cars at a marginal cost of $1 per car.If it is also possible for Rex to buy a high-quality hydraulic car smasher that cost $550 per year to own and if with this smasher he could dispose of cars at a cost of $.75 per car, it would be worthwhile for him to buy this high-quality smasher if he planned to dispose of

A) at least 1,410 cars per year.
B) no more than 700 cars per year.
C) no more than 1,400 cars per year.
D) at least 1,400 cars per year.
E) at least 700 cars per year.