Hi!
A function is when you can look at any number on the graph, and it only has one value in the line. For example, look at 2 on the y-axis. It only has one point on the line, but -2 on the y-axis has two points on the line. I hope that makes sense.
Therefore the answer is B. No, because some of the y-values are paired with 2 x-values.
Hope this helps! :)
-Peredhel