Please choose the correct answer to the question: Why are some rocks smoother and rounder than others?

Answer1: They have the shapes of the minerals from which they are made. Answer2: They were smoothed by the action of wind and water. Answer3: They were squeezed up through the soil. Answer4: They hardened in rounded pockets of soil.

Answer format: answer1/answer2/answer3/answer4
Answer: answer2