dialogue: M: Hi. I'm looking for Math 51B. Am I in the right place? W: No, this is Math 212. I think Math 51B is two doors down on the left, but I'm not sure. There should be a sign on the door, though.
question: Which room is the man looking for?
choice: Math 41B. Math 212. Math 51B.
answer: Math 51B.