Given the task definition and input, reply with output. 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: Sam is skating outside. He glides across the dirt with no problem, but falls when he skates on gravel. Question: Which ground has less friction? (A) dirt (B) gravel
dirt