Which area is characterized as the grassland region south of the Sahara Desert?

The Sahel is the region that serves as a transition zone between the Sahara Desert to the north and the more humid savanna and tropical areas to the south. It is characterized by semi-arid grasslands, which support various types of vegetation, including grasses and scattered trees. The climate in the Sahel is marked by a seasonal rainfall pattern, making it distinct from the desert environments surrounding it.

This region has significant ecological and economic importance, as it is inhabited by various pastoral and agricultural communities. The Sahel has also been the focus of recent concerns regarding climate change, desertification, and food security, highlighting its vital role in the livelihoods of millions.

In contrast, the other options represent different geographical features that do not fit the description of grassland south of the Sahara. The Qattara Depression is a low-lying area in Egypt; the Great Rift Valley is a geological formation that runs from the Middle East into East Africa; and the Congo Basin is a tropical rainforest region known for its dense forests, not grasslands. Therefore, the Sahel is the only area that matches the criteria given in the question.