You are given a sentence and a question. You're expected to write the correct answer based on the sentence.

Example Input: 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?
Example Output: pile of leaves

Example Input: Sentence: Mike knows that his porsche is quicker then his mazda. Question: If he drove both cars for the same amount of time, which would have gone the greater distance?
Example Output: porsche

Example Input: Sentence: Bob took his toy car outside to play with it. He rolled it on the street and then he rolled it in the grass. He noted that the toy car rolled much faster in the street. Question: Which surface caused more friction?
Example Output:
The grass