You are presented with the quiz "what is formed by deposition of sediment at the mouth of a river?" 

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 "deltas and estuaries are important habitats". 

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


 

    important habitats       