You will be given a definition of a task first, then some input of the task.
You are given a sentence and a question. You're expected to write the correct answer based on the sentence.

Sentence: Franklin found that if he slides a turtle on its back across a pool table, it slides farther than if he were to slide the turtle across a pile of leaves. He realizes this because there is less resistance on the pool table. Question: The difference in the length that the turtle slides across both surfaces can be attributed to which surface being rougher?
Output:
pile of leaves