Answer
$C$ represents line $m$
and $C^{-1}$ represents line $n$.
Work Step by Step
To identify $C(x)$ we consider $x=0$.
The $y$-intercept is: $C(0)=7.50 (0) +1500=1500$
Thus, $C$ represents line $m$
and $C^{-1}$ represents line $n$.