What does the Vertical Line Test determine?

The Vertical Line Test is a method used to determine whether a graph represents a function. According to the test, if any vertical line drawn through the graph intersects it at more than one point, the graph does not represent a function. This criterion is grounded in the definition of a function, which states that each input (or x-value) must correspond to exactly one output (or y-value). When a vertical line intersects the graph in two or more places, it signifies that a single x-value has multiple corresponding y-values, thus violating the definition of a function. Therefore, the correct answer accurately encapsulates the purpose of the Vertical Line Test in evaluating whether a given relation qualifies as a function.