runoff from sewage. deposition of sediment. an ancient glacier that passed through. an underground river flowing to the ocean.
I gave my students this multiple choice question: A delta at the mouth of a river is the direct result of

Only one answer is correct among these 4 choices:
- runoff from sewage.
- deposition of sediment.
- an ancient glacier that passed through.
- an underground river flowing to the ocean.

Could you tell me which one is correct?

deposition of sediment.