[masondixon]

If its your sister, if the police flirt with her, she will probably have an easier time in jail, maybe able to get preferential treatment. Good if you are the guilty criminal. So A.

If she is a suspect, then she would feel pressured to go along with the police's advances, because of the risk of retaliation for knocking back advances. So, B.

But for the victim of your sister's crime, she will want justice to be served, and will definitely go for B.