Answer:
B. Runoff from heavy rainfall forms narrow, shallow channels
Step-by-step explanation:
The rill erosion occurs at places that are stripped of vegetation, or do not have it naturally. The area in which this erosion occurs also has to be at a certain angle, thus it has to be a slope. When a heavy rainfall occurs, it manages to create runoff. The runoff over-saturates parts of the soil, and starts moving it downwards. As it moves it downwards, narrow, shallow channels are being formed. The water runs through this streamlets, or headcuts, moving the soil down with it, thus causing an extensive erosion of the area.