The best answer is option D, plant ground cover in unused fields
The unused land is exposed to soil erosion as there is no plantation or crops to hold the soil. These cover crops actively holdfast the top layer of soil firmly and thereby prevents it from being carried away either by wind or water. It also protect the soils against the splattering rainfall. Some common ground cover crops are – Annual Ryegrass, Oat, Barely , cow pea, sorghum etc.
