Deforestation generally decrease
(a) Rainfall
(b) Soil erosion
(c) Drought
(d) Global warming

Hint: The forest contains all forms of vegetation that affect reflectivity of the surface by absorbing more heat than bare sil which causes warm air carrying moisture from forest trees into the atmosphere.

Complete answer:
Deforestation includes regional and global climate change. Climate will become warmer due to the lack of humidity in deforestation regions and also patterns of rainfall have changed. Drought has become common. Trees help in removing carbon dioxide from the air and storing carbon in the trees and soil and releasing oxygen into the atmosphere.
- According to the UN conference deforestation is defined as ‘ land deflation in arid, semi- arid and sub- humid areas resulting from various factors including climatic variation and human activities.’
- Deforestation can cause flooding which makes all the water go away in the form of floods or even in the form of evaporation there won’t be any water left for usage. Lack of usable water will lead to drought.
- Deforestation is caused by; overgrazing, fuel wood, forest fires, landslides, population increase, industrialisation, urbanisation, road construction, inning, etc.
- It affects environmental damages like climate change, destruction of millions of species and greenhouse effect.
So, the correct answer is, ‘rainfall.’

Note:
- It causes biodiversity leading to disturbance in ecological balance work wide.
- It will lead to increase in carbon dioxide concentration and other air pollutants which results in global warming.
- The control measures for deforestation:
Reforestation - Growing more trees can successfully manage to reverse deforestation.
Legislation- By making suitable changes in the law, so that cutting trees in a forest.
Wildlife sanctuaries - This is important not only to save wildlife, but to save trees as well. Water management - Improper water management affects deforestation like by planning proper dams construction so that any one area isn’t deprived of water , while another area has abundance of it.