A B
P(A=1) = p P(B=1) = p
P(A=0) = 1-p P(B=0) = 1-p
P(A=1,C=1) = P(A=1) . P(C=1) = p.P(A=1,B=0) = p^2.(1-p) (1)
P(A=1,B=0) = P(A=1) . P(B=0) = p.(1-p) (2)
Since, (1) & (2) are not equal to each other, A & C are independent of each other when bits are biased.