Determine if the relation defines y as a function of x.

The vertical line test states that if any vertical line intersects the graph at more than one point, then the graph does not represent $y$ as a function of $x$. If every vertical line intersects the graph at most one point, then it is a function.

If we draw any vertical line across the graph, it will intersect the curve at exactly one point. For every $x$-value in the domain, there is only one corresponding $y$-value.

Since no vertical line intersects the graph at more than one point, the relation defines $y$ as a function of $x$.

The correct option is:
Yes, this relation defines $y$ as a function of $x$.