Concept:Soil erosion is prevented by farming practices that slow down running water and protect the topsoil.
Explanation:Overgrazing removes the grass cover that holds soil in place.
Deforestation removes tree roots that bind the soil together.
Bush burning destroys vegetation and exposes the soil to wind and water.
These three actions therefore increase erosion rather than control it.
Contour ploughing is a method in which ridges and furrows are made across the slope, not up and down it.
These ridges act as small barriers that break the flow of water down the hill.
The water is made to soak into the ground instead of carrying away the topsoil.
This makes contour ploughing an effective way of controlling soil erosion.
Answer:B. Contour ploughing