Step 1: Concept
Contour bunding is a soil conservation technique where small earthen barriers (bunds) are built across the slope along the contours of the land.
Step 2: Meaning
By breaking the length of the slope, these bunds prevent water from picking up high speed as it flows downhill.
Step 3: Analysis
Slower water flow means less topsoil is washed away, and more water has time to soak into the ground (recharge).
Step 4: Conclusion
It is primarily used to control water erosion on sloping lands.
Final Answer: (B)