The answer is C. Explanation: The line isn’t a straight line, so it can’t be a linear line. Then, do the vertical line test to see if the line is a function (to do this, draw a vertical line through the graph, and see if it passes more than one point on the graph. If the vertical line passes any more than one point on the graph on any spot, it is not a function), and since the graph fails the vertical line test, it is not a function. Therefore, the answer is C.
