We are given three graphs and asked to decide if they correspond to "functions". We recall that a graph to represent that of a function must pass what is called: the VERTICAL LINE TEST.
Such test is the drawing of perfectly vertical lines thatgo across the graph, trying to decide if at any point of the graph the vertical line intercects the graph more than once.
As we draw vertical lines in the first graph, we see that we can draw quite many vertical lines that cross the graph in MORE than ONE point. In fact, many vertical lines will cross the graph in TWO points. We conclude that such first graph doesn't pass the vertical line test and therefore it is NOT a function.
Let me dra the vertical lines and show you on the graph the intersections I am talking about. Give me please a few minutes to draw and upload an image.
I have marked in red vertical lines that show (with small crosses) the points where they intersect the original graph. As you can see, the same problem repeats in the other two graphs, where you see again that the graphs DON'T pass the vertical line test, because the vertical lines cross the graph in MORE than ONE point.
Therefore you should select a NO for all three graphs. They are NOT representing functions.