Explanation:

1, 2, 3 and 4

Fertilizers (1) can impact soil erosion, especially if they are applied in excess or improperly managed, leading to nutrient runoff and soil degradation.

Grazing (2) by livestock can contribute to soil erosion, particularly if overgrazing occurs, which removes vegetation cover and exposes soil to erosion by wind and water.

Topography (3) plays a significant role in soil erosion. Steep slopes are more prone to erosion compared to gentle slopes due to increased runoff and gravity's influence.

Organic Matter (4) can help reduce soil erosion by improving soil structure, increasing water infiltration, and promoting the growth of vegetation, which helps stabilize soil.

Therefore, option 4 (1, 2, 3, and 4) is the correct choice