Given the following. U = {1,2,3,4,5,6,7,8,9,10,11}

A = {3,4,6,7,11}

B = {4,5,6,8}.

Find (A U B)' U B.

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.