What defines a region in geographic terms?

In geographic terms, a region is defined by a specific area that is identified by unique characteristics. These characteristics can be physical, such as climate, landforms, or ecosystems, or they can be human-made, including cultural practices, economic activities, or political boundaries. Regions can be distinguished from one another based on these unique features, which help geographers and researchers understand spatial relationships and the diversity of places within the world.

Other options describe certain geographic concepts but do not encompass the broader definition of a region. An expanse of uninhabited land does not account for the cultural or economic characteristics that can define a region. A city as a central hub refers to urban geography but doesn't capture the broader attributes that classify an entire region. Similarly, a nation with its own government represents a political entity rather than a region defined by unique qualitative characteristics. The idea of uniqueness is key in defining a region, making the first option the most accurate.