Which of the following is equal to (A∪B)′∩(A′∪B′)(A \cup B)' \cap (A' \cup B')(A∪B)′∩(A′∪B′)?
A′∩B′A' \cap B'A′∩B′
A′∪B′A' \cup B'A′∪B′
A∩BA \cap BA∩B
∅\emptyset∅