Final answer:
Belgium has especially fertile soil covered by deposits of loess, a rich sediment left by glaciers.
Step-by-step explanation:
The country with especially fertile soil covered by deposits of loess, a rich sediment left by glaciers, is c) Belgium. Loess is a windblown sediment that is typically yellowish-brown or gray in color, and it is known for its high fertility. The glaciers in the past have deposited this sediment in various regions around the world, including parts of Belgium.