We have two points: (0,0) and (4,-3)
The equation we use to find slope is (y2 - y1) / (x2 - x1)
The slope would be -4/3
your y-intercept is 0, since the line intercepts the y-axis at 0.
Now, you can construct your equation:
A. y = (-4/3)x
Hope this helps! :)