Please choose the correct answer to the question: Biotic forces can cause changes to the surface of Earth. Which is the best example of living organisms causing weathering?

Answer1: Beavers building a dam across a stream. Answer2: Cattle walking and grazing in a grassland. Answer3: Salmon making nests for their eggs in a stream. Answer4: Tree seedlings growing and forming cracks in rocks.

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