Please choose the correct answer to the question: The iron in iron-rich red soils may not be in a form that can be taken up by tree roots. As a result, leaves and needles may look yellow. Some trees release acids that convert iron in soil to a usable form. This change in soil chemistry is a type of which process?

Answer1: deposition Answer2: weathering Answer3: precipitation Answer4: photosynthesis

Answer format: answer1/answer2/answer3/answer4