Answer:
A.
Explanation:
The vertical line test is a way of finding out if a relation is a function.
Graph the relation.
Then imagine a vertical line moving from left to right over the graph of the relation.
If the vertical line intersects at most one point of the graph in any position you place the vertical line, then the relation is a function.
This function passes the vertical test since it never intersects more than one point on the vertical line at a time.
Answer: A.