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.
One example: Sentence: Jacob and Benny are squatting at the gym. Jacob has thin frail legs and Benny has big strong legs. Question: Who squats less weight? (A) Jacob (B) Benny
Solution is here: Jacob
Explanation: Typically, people with thin frail legs squat less weight than people with big strong legs, so the answer is Jacob.

Now, solve this: Sentence: Tim threw a pebble down the mountain effortlessly, and it was out of site in seconds.  Bob rolled a boulder down the mountain, and after a minute of heaving, it finally descended, gaining speed as it went. Question: Which was heavier? (A) the boulder was heavier (B) the pebble was heavier
Solution:
the boulder was heavier