Which of the following is a function?

Click on the graph until the correct graph appears.

The correct graph should have x values that have no more than one y value.

Step-by-step explanation:

A the inputs (x values) of a function can have no more than one y value. This is a "fact" for functions. So you should click on the graph until you see a graph where every x value has exactly 0 or 1 y value.