Answer
The graph rises (is increasing) from left to right therefore as the number of miles driven increases (as x increases) the cost also increases (y also increases).
Work Step by Step
(Refer to the graph in the attached image below for the graph of $C(x)$.)
$\\\\$Based on the graph, it can be observed that as the number of miles driven increases, the cost also increases.
$\\$This is because as you move to right of the graph (increasing value of miles driven), the graph rises (which mean that the cost also increases).