Exhibit $2$

$7.$ Use Exhibit $2.$ Point $F$ is the output combination of $500$ cars and $60$ houses. Which of the following is $($are$)$ correct?

$($x$)$ The opportunity cost of the first $500$ cars is $40$ houses and the opportunity cost of the first $60$ houses is $300$ cars.

$($y$)$ The opportunity cost of the $40$ th house is more than $4\mathrm{.}8$ cars but less than $5\mathrm{.}2$ cars and the opportunity cost of the $70$ th house is greater than $12$ cars but less than $13$ cars.

$($z$)$ The opportunity cost of the $300$ th car is more than $0\mathrm{.}076$ house but less than $0\mathrm{.}082$ house and the opportunity cost of the $600$ th car is more than $0\mathrm{.}18$ house but less than $0\mathrm{.}21$ house.

A$.(x),(y)$ and $(z)$

B$.(x)$ and $(y),$ only

C$.($x$)$ and $($z$),$ only

D$.($y$)$ and $($z$),$ only

E$.($x$)$ only