Explanation:

all are correct

Contour bunding or contour farming or Contour ploughing is the farming practice of plowing and/or planting across a slope following its elevation contour lines. These contour lines create a water break which reduces the formation of rills and gullies during times of heavy water run-off; which is a major cause of soil erosion. The water break also allows more time for the water to settle into the soil. In contour plowing, the ruts made by the plow run perpendicular rather than parallel to the slopes, generally resulting in furrows that curve around the land and are level. This method is also known for preventing tillage erosion.Tillage erosion is the soil movement and erosion by tilling a given plot of land. A similar practice is contour bunding where stones are placed around the contours of slopes.Contour ploughing helps to reduce soil erosion.