Try answering the question at home on your own before looking up the answer. Try to vocalize your answer as you attempt to problem solve it to practice your communication skills. Then look up the answer and adjust accordingly. Whether you answer the question before the interview is beside the point. You want to go through the whole problem-solving process, communicating clearly when this question is posed.

"Well, in order for this to make sense, since there are only three moves involved here, the geometrical shape of the route taken cannot possibly be a square, right? So in order to have done so in three moves, and end up where I started, it would have to be a triangle. So in order for that to be the case, where on Earth would I have to be if I were to end up where I started in three moves like that? It would have to be a fixed point on the planet. The planet is spherical, but if I am going walking one mile south, and then one mile west, and then one mile north, those are fixed directions that cannot be altered, so that would mean it was a direction that is fixed, such as The North Pole?"