The slope is -3
210 so C.
Hope this helps :)
See image below
We want to draw a line through all points with a y-coordinate of -3; first let's observe some of these points: (-3,-3), (0,-3), (1,-3), (10,-3) are all part of this line.
We can see that what all these points have in common are that they have -3 in the y axis. Therefore, the graph of the line would be y = -3
This line is drawn in the graph below.