If P(A)=0.6P(A) = 0.6P(A)=0.6, P(B)=0.5P(B) = 0.5P(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
0.8