Given P(A)=0.5,P(B)=0.5,P(A)=0.5, P(B)=0.5,P(A)=0.5,P(B)=0.5, and P(A∪B)=0.8P(A \cup B)=0.8P(A∪B)=0.8, what is P(Ac∣Bc)P(A^c | B^c)P(Ac∣Bc)?
0.2
0.4
0.5
0.6