Answer:
Number 1 would be a line, you can put values of x and you will get values of y which give you points of that plot, or viceversa.
Number 2 is an horizontal line, as y remains the same all time, in this case, we find an horizontal line which covers all the x-axis.
Number 3 is a vertical line, as x remains the same all time, in this case, we find a vertical line which covers all the y-axis
So the solution is the third box
