Please choose the correct answer to the question: Roger poured water over a pile of sand. Some of the sand washed away. This process is similar to which of the following?

Answer1: The eruption of a volcano Answer2: The erosion of the walls of a canyon Answer3: The uplifting of mountain ranges Answer4: The forming of dunes or mounds in a desert

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