Answer:
B.
Step-by-step explanation:
Plains are one of the major landforms of the earth. They are formed by both- destructive forces and constructive forces.
In the destructive process, the rivers and their tributaries flow down from mountains or slopes and carry sand, silt, and stones with them. And the particles that are carried by the river are deposited along their paths and valleys.
So, weathering keeps the plains flat while deposition brings more sediments and soil to the surface.
Therefore, option B is correct answer.