Where does a river floodplain come from? A. A river erodes the land and deposits sediments as it erodes sideways.
B. Landslides from the river valley walls cause soil and rock to make the floodplain.
C. Flooding along a river removes all the sediment, revealing the floodplain below.
D. As the land gets steeper the river cuts farther and farther down in the soil and rock.