The correct answer is - D. Pampas.
The Pampas in Argentina is an area that is naturally covered with grasses. It is a semi arid region that experiences seasonal rain. The soil is very fertile because of the humus layer created by the decomposition of the grasses, and also because the climate is enabling a quick decomposition of the biomass, thus the soil is able to quickly recover.
The Pampas is heavily used nowadays for agriculture in Argentina, and it is considered as one of the best places for agriculture in the world. Most of the agricultural production in Argentina is in this area.
