The conditional probability P(A/C) is given by
[tex]P(A|C)=\frac{P(A\cap C)}{P(C)}[/tex]If event A is independent to event C, we can write
[tex]P(A|C)=\frac{P(A)\cdot P(C)}{P(C)}=P(A)[/tex]Similary, if event B is independent to event C, we get
[tex]P(B|C)=\frac{P(B)\cdot P(C)}{P(C)}=P(B)[/tex]Then, by comparing both results we can see that event A is more likey than event B.