y = mx, where m is slope.
Slope is [tex] \frac{rise}{run} [/tex], where:
rise --> vertical(y axis)
run --> horizontal(x axis)
y=4x: slope = 4
rise = 4
run = 1
So go up 4, and right 1
If you plot points starting at (0, 0) you get the graph shown to the right; or vice versa, counting the rise and run and finding the slope.
Answer: D