I'm still confused as to how this works because, when you ask the question of the girls, you can only ask ONE girl ONe time, and you don't know who you're asking.

Say the sisters are lined up in a row...

Scenario 1:

A is the oldest. B is the middle. C is the youngest. You ask A, "A, is B younger than C?" She will honestly answer, "Nope!" You have no idea which sister you have asked. You either 1) assume she is telling the truth and marry sister C - yay!; OR 2) assume she is lying and marry sister B - shit! 50/50 chance.

Scenario 2:

A is the youngest. B is the middle. C is the oldest. You ask A, "A, is B younger than C?" She will lie and say, "Nope!" You have no idea which sister you have asked. You either 1) assume she is lying and marry sister C - yay!; OR 2) assume she is telling the truth and marry sister B - shit! 50/50 chance.

Scenario 3:

A is the middle. B is the oldest. C is the youngest. You ask A, "A, is B younger than C?" She could lie or tell the truth, and you could assume she's lying or assume she's telling the truth, but it won't matter because as long as you marry B or C, you're good. This is the best case scenario. However, you still have no idea, definitively, if you're picking the oldest or youngest because you don't know that you're asking the middle.

Am I missing a clue or a rule that makes this work? Help. :(