To find the domain, NSS....list all the points from left to right......note that we have
(-4 ,-1), (-1, 4), (1, 1) , (4,1).......now list the x values in order.....so we have [ -4, -1, 1 , 4 ]....and this is the domain
To find the range....list the points in order from the bottom of the graph to the top of the graph......
( -4, -1) , (1,1) , ( 4,1), (-1,4) .....note that the ones in red can be listed in any order...
Now......list these points y values in order.........,so we have [ -1 , 1 , 4 ]....and this is the range
This is a function......as long as we don't have two points with the same x value but two different y values, we have a function
Also......its a function because it passes the vertical line test....that is.....any vertical line drawn on the graph will only intersect one point at a time
Do you see what the correct answer is ???