Please choose the correct answer to the question: Several horses grazed in a fenced area across from a home. On rainy days, soil would wash down a slope and run toward the home. After the horses were moved a few years later, the soil no longer washed down when it rained. What could account for this change?

Answer1: The grass grew and kept the soil intact. Answer2: The fence kept the soil contained. Answer3: The soil was completely gone. Answer4: The amount of rain decreased.

Answer format: answer1/answer2/answer3/answer4