SOLUTION
We want to find (A ∩ B)’ we have to first find (A ∩ B), that is elements that are common to both A and B, elements seen in A and also seen in B
So

Now (A ∩ B)’ are elements seen in the universal set U that are not in (A ∩ B). These are

Hence the answer is c) {1, 3, 4, 5, 6, 7}