Contour bunding is a method of conservation used in

Contour bunding means building earthen ridges (bunds) along the contour lines of sloping cultivated land. Each bund slows surface runoff, reduces soil loss and lets more water soak in. It works on gently to moderately sloping farmland where rain-driven erosion is the problem, such as hill slopes and the rainfed uplands of the Deccan. The method rests on the slope, and none of the three options describes that terrain.

• A is wrong. Desert margins with strong winds face wind erosion. The remedies are shelterbelts, wind breaks and strip cropping. Bunds along contours do nothing against wind.
• B is wrong. Low, flat plains liable to flooding need embankments, drainage channels and flood control. On flat ground a contour bund would simply trap water and worsen waterlogging.
• C is wrong. Scrublands with weed spread need clearing, controlled grazing or weed management, not bunding.

Connect this to watershed development under the Integrated Watershed Management Programme and soil and moisture conservation in rainfed farming, which are standard Mains topics on agriculture and rural development.

Trap: Aspirants treat contour bunding as a generic soil-conservation tool and pick A because desert margins are an obvious erosion case. Ask first what terrain the method needs.