The answer is Option 2
Its not a function
The domain and range of the function is shown at the various endpoints of the graph.
At every point you can always identify a value for x (the input value) and also a corresponding value for y (the output value).
Please note the endpoints marked in blue.
These are the endpoints, and for every point, you will have (x, y).
However, note that at the endpoints, the values of y remains the same.
For every relation to be a function, there must be exactly one corresponding y value for every x value. As shown by the blue markings on the graph, the x values on the horizontal axis both have the same y value (which is zero).
Hence, the relationship shown by the graph is not a function