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 glider moves at a lower rate of speed through the treetops then through the air. Question: Which surface is smoother? (A) treetops (B) air
Output:
B