Answer:
function
Step-by-step explanation:
The verticle line test is basically seeing if it is a function
It is a function when the verticle line touches only one point on the graph at once
For example, if the graph was a circle, and u drew a verticle line through it, it would touch two points on the graph, so it is NOT a function
But for this parabola, if you draw a verticle line at any point, it only touches one point of the graph, so it is a function
