Which of the following regions is known for its vast undeveloped areas?

The Great Plains is recognized for its expansive, predominantly flat terrain, which is characterized by agricultural land, prairies, and areas that remain relatively undeveloped. This region includes significant portions of the central United States and parts of Canada, featuring vast stretches of grasslands that have not undergone extensive urbanization or industrial development. The relatively low population density contributes to the continued presence of large undeveloped areas, allowing for a native ecosystem that includes a diverse range of wildlife and native plants.

The other regions mentioned each have characteristics that differentiate them from the Great Plains: the Great Basin is noted for its mountain ranges and deserts; the Gulf Coast is defined by its coastal geography and urban development around major cities; and the Sahara is a vast desert known for its arid conditions rather than expansive grasslands.