4. Vegetation, conservation and reestablishment of forest and wetlands can prevent further... 1. irrigation
2. soil degradation
5. crop production
4. deforestation

Vegetation, conservation, and reestablishment of forests and wetlands can prevent further soil degradation.

Explanation:

The soil has been damaged badly all over the world. The main reason behind this has been the fact that a lot of the vegetation and wetlands have been destroyed because of human activities. The vegetation is the best natural protector of the soil, so once it is removed the soil is prone to large-scale erosion, while the wetlands are able to accumulate the excess water and prevent it from reaching the soil and damage it.

The allowing the vegetation to regrow naturally and to help it with reforestation, as well as conserving them, the soil will get its natural protection again, so the soil degradation will be stopped or at least minimized, while also it will get richer and better over time. Reestablishing the wetlands too will help in the preservation of the soil as they will accumulate the surpluss of water, so that water will not reach the soil or at least a big portion of it won't, so the soil will not undergo a sudden and big erosion.

c, this answer is productivity.