Answer
The vertical line test shows if any x value does not correspond to exactly one y value.
Work Step by Step
If a given x value corresponds to two y values, then for that given value x, there will be 1 point directly above another point. Consequently, a vertical line would go through two points in this scenario. Thus, if there are two or more y values corresponding to a given x value, a vertical line will intersect the graph at multiple points.