Task: Question Answering
Input (English): 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?  
 (A) deposition (B) weathering (C) precipitation (D) photosynthesis
Output (English): B