Answer: D) Neither proportional nor non-proportional
A non-proportional graph would be curved in some way, but we have a straight line. So we can rule out choices A and B. Another term for "non-proportional" would be "nonlinear".
The graph is not proportional either because the straight line would need to go through the origin (0,0). So we would have x = 0 and y = 0 pair up together.
This leaves choice D as the answer.