What is the primary geographic feature of western Oklahoma?

The primary geographic feature of western Oklahoma is indeed the Great Plains. This region is characterized by flat, grassy areas that stretch across several states in the central United States. The Great Plains are known for their broad, open landscapes, which are conducive to agriculture and ranching, making this area a significant agricultural hub.

In contrast, the other options do not accurately represent the geography of western Oklahoma. The Rocky Mountains are located much farther west and do not extend into Oklahoma. The Ozark Mountains are situated to the east of Oklahoma, predominantly affecting the geography of Arkansas and parts of Missouri. Additionally, the description of the region as primarily forested hills does not apply to western Oklahoma, where the landscape is mostly flat to gently rolling plains, distinguishing it from heavily forested areas found in the eastern part of the state.