A Businessman Is Considering How Many Limousines to Purchase When

Multiple Choice

A businessman is considering how many limousines to purchase when he starts up a limousine service.Below are his estimates of the number of limousine rentals the service will make during a year,depending on the number of limousines available.
After paying all non-interest expenses,the owner expects to net $10 per rental.Each limousine costs $50,000.How many limousines should he purchase if the real interest rate is 4.5%?

A) 0.
B) 1.
C) 2.
D) 3.
E) 4.