According to De Morgan's Law for sets, (AcupB)′(A \\cup B)'(AcupB)′ is equal to:
A′capB′A' \\cap B'A′capB′
(A′cupB′)′(A' \\cup B')'(A′cupB′)′
A′cupB′A' \\cup B'A′cupB′
AcapBA \\cap BAcapB