You are given a sentence, a question and two answer options ('A' and 'B'). Your task is to find the correct answer (return the string of the correct option, not 'A' or 'B') for the given question.

Sentence: Annabel rolls a pomegranate down two boards, one with knots and one without. When it rolls down the board without knots, it has less friction than when it rolls down the board with knots. Question: Which board is rougher? (A) wood board with knots (B) wood board without knots
wood board with knots