A farmer wants to expand his fields, but only has hills left. He is worried about water erosion because of the rate at which water is pulled down the hills during rainstorms. What can this farmer do to reduce the water erosion he fears?
A. Rotate his crops so that there is permanent groundcover.
B. Use contour plowing on the hills.
C. Install silt fences at the bottom of the hills.
D. Reshape the hills with terraces.