Correct Option: D

Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned. It is also known as slash and burn cultivation. This system often involves clearing of a piece of land followed by several years of wood harvesting or farming, until the soil loses fertility. Once the land becomes inadequate for crop production, it is left to be reclaimed by natural vegetation, or sometimes converted to a different long term cyclical farming practice. The ecological consequences are often deleterious. Shifting agriculture has frequently been attacked in principle because it degrades the fertility of forest lands of tropical regions..