You are presented with the quiz "Sediment is dropped at the mouth of a river by water when what happens?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "adelta is formed by deposition of sediment at the mouth of a river by water fanning out" and "when the river slows, it drops the sediment in a wide fan, a delta". 

So, what's the best answer to the question?


 

    rivers slow       