Hello!
In a function, each input must have one output. Therefore, if two parts of the graph are on the same x-value, it is not a function.
To test this, we can use the vertical line test. When we move a vertical line across the graph, if it any time it hits two points on the graph, it is not a function.
For example, if our vertical line went through the line x=2, it would hit our graphed function twice. This means 2 has two outputs, so it is not a function, and our answer is A) No, it fails the vertical line test.
I hope this helps!