the land drained by a river and its tributaries the land formed when rivers create estuaries and marshes the land at the mouth of a river where water flows into the ocean the land formed as a result of a river flooding
I gave my students this multiple choice question: Which best describes the characteristics of a river basin?

Only one answer is correct among these 4 choices:
- the land drained by a river and its tributaries
- the land formed when rivers create estuaries and marshes
- the land at the mouth of a river where water flows into the ocean
- the land formed as a result of a river flooding

Could you tell me which one is correct?

the land drained by a river and its tributaries