flat lands many sinkholes rugged peaks long rows of ridges
I gave my students this multiple choice question: Rivers leave behind small pieces of rocks after they flood. These small pieces of rock form a floodplain. Which words best describe a floodplain?

Only one answer is correct among these 4 choices:
- flat lands
- many sinkholes
- rugged peaks
- long rows of ridges

Could you tell me which one is correct?

flat lands