Task: Question Answering
Input (English): Biotic forces can cause changes to the surface of Earth. Which is the best example of living organisms causing weathering?  
 (A) Beavers building a dam across a stream. (B) Cattle walking and grazing in a grassland. (C) Salmon making nests for their eggs in a stream. (D) Tree seedlings growing and forming cracks in rocks.
Output (English): D