Concept: Bush burning damages the soil by removing its natural organic layer.
Explanation: Bush burning involves setting vegetation on fire, which generates strong heat in the topsoil.
This high temperature burns up dead leaves, roots, and humus present on or near the surface.
Organic matter is the part of soil that improves water retention, nutrient supply, and soil structure.
Once it is destroyed, the soil becomes less fertile and more prone to erosion.
Bush burning also reduces soil organisms and may produce ash that adds some potash, but the main harmful effect is the loss of organic matter.
Destroying weed seeds is not a detrimental effect, and sterilizing the soil is not the major direct consequence.
Therefore, the correct option is the one that identifies the destruction of soil organic matter.
Answer: A. destroys soil organic matter.