text: you are locked in a room that has only two doors, [and no windows],  to escape from? and each door has a guard sitting outside it.   these doors are your only means of getting out of the room.  there is absolutely no other way to leave. you know that one guard is an absolute liar, he will never tell the truth no matter what.   the other guard is always truthful, in fact he can not tell a lie ever to you or anyone else.   you will be allowed to ask one question only, and you can only ask that one question to one guard.   you do not know which guard is the liar and which tells the truth.   what would your one question and your response be? i'd ask guard a what guard b would say to the question "which is the door to freedom?" and then choose the opposite door.  there is guaranteed to be one lie so i know to choose the other door.