Sarah did figure it out correctly, though. She then said it was a piece of cake and led the labyrinth to change and drop her ass down into the oubliette. Labyrinth "Where everything seems possible and nothing is as it seems."
She wasn't looking for a safe door what she wanted was a door that leads to the goblin city than when she fell and the hands had her she picked the wrong way if she went up she might of gone to a path leading her where she wanted to go.
Sarah picked the door that led to the castle, which was the point of the two doors. One leads to the castle, the other one leads to certain death. If, as mrscollector said, she would have told the helping hands to bring back up to the top she would have been on path to the castle. Whether there would have been more traps or not well never know, but the door she chose was safe compared to certain death.
The point of the situation is you only get one question, but you have to find out which door doesn't lead to death while also figuring out which one will lie to you. You only get one question so you have to figure out Both answers from
The same question, you could easily find out who is telling
The truth, but without assurance as to what door won't lead to death, what's the point?
The question usually involves both finding out which one is a liar and which one is honest, as well as figuring out which door to open, in a single question. Asking something like this will tell you who lies and who is honest- but it doesn't tell you which door to pick, and there goes your question
The same question, you could easily find out who is telling
The truth, but without assurance as to what door won't lead to death, what's the point?