The correct answer is:
A. When the pea hit the paper towel, the paper towel applied an equal but opposite force on the pea.
This explanation is based on Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When the pea strikes the paper towel, it exerts a force on the towel, and in response, the towel exerts an equal force back on the pea, causing it to bounce off.