Let A and B be two independent events on a sample space . If P(A) = 34

Let A and B be two independent events on a sample space Ω. If P(A) = 3∕4 and P(AB′) = 21∕40, then the probability of event B is

(a) 3∕10

(b) 7∕10

(c) 2∕5 (d)3∕5 (e)9∕40