soil can be washed away. soil creation may take years. river sediment forms a delta. planting grass protects the soil.
I gave my students this multiple choice question: Pouring water over a sloping tray of soil demonstrates how

Only one answer is correct among these 4 choices:
- soil can be washed away.
- soil creation may take years.
- river sediment forms a delta.
- planting grass protects the soil.

Could you tell me which one is correct?

soil can be washed away.