For what value(s) of k will the relation not be a function? c r = {(k^3–5k^2+3k, −5), (−k, 4)}

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.