The best option is C. desertification.
When land has been over farmed or overgrazed , desertification occurs.
Desertification is said to be a process of degradation of land whereby land that was previously biologically productive is changed into a barren, unproductive land.
Desertification can be brought about by poor use and destruction of natural resources such forest and natural vegetation. Such include:
1. Excessive tree felling or cutting
2. Unsustainable farming practices which lead to loss of soil fertility.
3. Removal of vegetation cover.
4. overgrazing.
5. Uncontrolled fuel wood gathering or collection.
