Soil erosion is the removal of top soil by the agency of water (water erosion) and wind (wind erosion). Soil erosion is of two types, natural and anthropogenic.
Natural or geological erosion is extremely slow removal of top soil due to rain water or wind.
Anthropogenic soil erosion is caused by removal of plant cover through over grazing, litter collection, tree felling, leaving the soil unprotected during agricultural operations.
Top soil is rich in organic and mineral nutrients. If top soil is removed the productivity of land is reduced.
So, the correct answer is option A.