Scarlet is a manager at the local Apple store. In determining whether to buy a few additional iPhones, Scarlet chooses at the
margin when she compares the:
total revenue from sales of iPhones to the total cost of buying iPhones.
O extra revenue from selling a few additional iPhones to the extra cost of buying those iPhones.
extra revenue from selling a few additional iPhones to the average cost of buying those iPhones.
revenue from selling iPods to the revenue from selling iPhones.