All three agricultural practices help in carbon sequestration: (1) Contour bunding reduces soil erosion and maintains organic matter in soil, helping sequester carbon. (2) Relay cropping (growing a second crop before harvesting the first) maintains continuous soil cover and adds organic matter, helping carbon storage. (3) Zero tillage (no-till farming) is specifically recognized as an important carbon sequestration practice — it avoids ploughing which releases stored soil carbon. All three contribute to keeping carbon in the soil rather than releasing it.