Question

Which relation is a function?

Answer 1

Bottom left graph.

Explanation:

The one shaped like a V as it is the only one to pass the vertical line test.

(For it to be a function any vertical line drawn only passes through the graph once.)

Answer 2

The third option (the one that looks like a V but isn't sideways.

To find a function use the vertical line test. To do that you see if a vertical line passes through one or multiple points. If it passes through more than one point anywhere then it isn't a function.