What must be done to material above an "A" horizon?

The correct choice emphasizes the importance of managing soil layers, particularly in the context of site assessment and land use. The "A" horizon, often referred to as the topsoil layer, is crucial for plant growth and contains a high concentration of organic matter and nutrients. When assessing soil for purposes such as construction or agricultural development, it may be necessary to remove the material above the "A" horizon to ensure that the underlying soil structure is conducive to the intended use.

This removal is often done to expose soils that are more stable or suitable for building, as the material above the "A" horizon may be less compacted or have different properties that do not support construction activities. Maintaining soil health and structural integrity is essential for successful land use, which is why the removal process must be approached carefully, ensuring that any necessary measures are taken to support sustainable practices post-excavation.

In contrast, leaving the material above the "A" horizon or preserving it for future studies may not align with practical site preparation needs, particularly in contexts where development or alteration of the land is required. Similarly, while it might seem appealing to consider the above layers as safe for building, those layers can indeed compromise the stability and fertility of the soil if not assessed properly