Concept:Overgrazing harms the soil, whereas improvement of soil structure is a beneficial effect.
Explanation:Overgrazing removes protective vegetation cover.
This exposes the soil to erosion by wind and water.
Heavy trampling by livestock leads to soil compaction.
Continuous grazing reduces organic matter and depletes soil nutrients.
Improving soil structure is not a harmful result of overgrazing.
Hence, it is not an effect of overgrazing.
Answer:A. Improvement of soil structure