Instructions: You are given a sentence, a question and two answer options ('A' and 'B'). Your task is to find the correct option for the given question. Write down the answer index: 'A' or 'B'.
Input: Sentence: A matchbox can slide across a greenhouse floor, but it doesn't move as fast as when it is slid across the backyard. Question: Which surface is the smoother one? (A) greenhouse floor (B) backyard
Output:
A