Question

Let A1, ..., An be collectively exhaustive and let B be an event. Then Pr(B) >=
a) Σ from 1 to n of Pr(B|Ai)Pr(Ai)
b) Σ from 1 to n of Pr(B|Ai)/Pr(Ai)
c) Σ from 1 to n of Pr(Ai|B)Pr(B)
d) Σ from 1 to n of Pr(Ai|B)/Pr(B)