Answer :
All of these factors pose a potential and real threat to agricultural sustainability, and are all interconnected. If the water is polluted, the crops will eventually begin to fail.
Answer is a. Erosion.
The greatest threat to agricultural sustainability is erosion. Erosion is a naturally occurring process that affects all land forms. In agriculture, soil erosion is process in which top soil of the land is wear away by different natural agents or physical forces such as water and wind. Soil erosion is also occurs due to farming activities such as tillage. Irrespective of eroding agents, erosion involves three distinct actions. These actions are soil detachment, movement and deposition. Topsoil which is rich in organic matter carried away to other places.
