Answer:
It's the bottom left graph.
Step-by-step explanation:
To tell if a graph is a function you do the vertical line test. If the line passes through more than 1 point, its not a function.
You can see it in the pic below that all the other graphs, a vertical line passes through more than 1 point. I highlighted those points so you could see. But the bottom left graph the vertical lines only pass through one point each time. So that is a function.
