#### Answer

Option (d)

#### Work Step by Step

RECALL:
For the linear function $f(x) = mx + b$:
$b$ is the y-intercept, which is the value of the function when $x=0$, and
$m$ = slope, which is the average rate of change.
The given function has:
$ x$ = the number of days the car is driven
$m = 40$, the number of miles a car is driven per day
$b = 12,500$ miles
Thus, the function $N(x)$ that models the situation is:
$N(x) = 40x + 12,500$
Therefore, the answer is Option (d).