Which of the following helps in preventing soil erosion?

The correct option is A Afforestation
The removal of the top layer of soil by the action of air, water, etc., is known as soil erosion.

$\bullet$ Afforestation is the process of planting trees to increase plant cover. The roots of the trees bind the soil together strongly and prevent soil erosion.

$\bullet$ Deforestation and overgrazing lead to the removal of the top layer of soil as the trees and patches are removed and do not recover quickly. Thus, soil erosion takes place.

$\bullet$ Excessive use of fertilizers causes the soil to lose its nutrients, thereby causing soil infertility. This hampers the growth of plants and thus, causes soil erosion as plants cannot hold the soil with their roots.