The two regions of Africa that are most vulnerable to desertification are the Sahel and the Savanna. These regions are already dry and have fragile soils, and climate change, overgrazing, and deforestation are making the problem worse.
The correct answer is "Sahel and the Savanna."
The Sahel is a semi-arid region that lies south of the Sahara Desert. It is characterized by low rainfall and poor soils. The Savanna is a grassland region that lies south of the Sahel. It has more rainfall than the Sahel, but its soils are still vulnerable to erosion.
Desertification is the process by which land becomes increasingly arid and less productive. It can be caused by a number of factors, including climate change, overgrazing, and deforestation.
The Sahel and Savanna are particularly vulnerable to desertification because they are already dry regions with fragile soils. Climate change is making these regions even drier, and overgrazing and deforestation are further damaging the land.
The map of Africa you provided shows that the Sahel and Savanna are the two regions that are most at risk of desertification. The map also shows that desertification is already a serious problem in these regions.