Describe what soil erosion is.

Soil erosion refers specifically to the displacement of the upper layer of soil, which is crucial for the growth of crops and other plants. This top layer, often rich in organic matter and nutrients, is vital for maintaining soil fertility. When erosion occurs, whether through water, wind, or human activity such as farming, the topsoil is removed, leading to a decrease in soil quality. This reduction in fertility can ultimately result in lower agricultural productivity, as crops depend on healthy soil for their nutrient supply.

In contrast, compaction (mentioned in another option) relates to how soil particles are pressed together, which can lead to reduced water infiltration and root penetration but does not involve the physical displacement of the soil. The process of soil becoming too dry describes a state of dryness rather than an erosive process, and the natural formation of soil refers to soil development over time rather than its loss through erosion. Therefore, the correct understanding of soil erosion revolves around the removal and loss of the productive upper layer of soil, which is accurately captured by the selected answer.