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: A dog toy thrown across a grassy field travels at a lower rate of speed compared to one thrown across a dirt field. Question: Which field is the least rough? (A) grassy field (B) dirt field
dirt field