If A∩B′=ϕ then prove that A=A∩B and hence show that A⊆B.
If A and B are two events such that P (A) ≠ 0 and P(B|A) = 1, then.
(A) A ⊂ B
(B) B ⊂ A
(C) B = Φ
(D) A = Φ