Which natural feature is key to sustaining an oasis?

The feature that is key to sustaining an oasis is water sources. An oasis is typically a fertile area in a desert or semi-desert environment where water can be found, often due to underground springs or aquifers that surface. This water is essential for supporting vegetation and wildlife, making it a critical factor for an oasis’s existence and sustainability.

While mountains, rivers, and forests are important natural features in various ecosystems, they do not directly contribute to the formation of an oasis in the same way that a water source does. For instance, mountains can influence climate and weather patterns, potentially affecting rainfall in an area, but they do not provide the water needed for an oasis. Similarly, rivers are vital to many ecosystems, but oases are often located in areas where river systems are absent. Forests, while critical for biodiversity and ecology, are not typically found in arid desert environments where oases occur. Thus, the presence of reliable water sources is the fundamental characteristic that defines and sustains an oasis.