The correct order of terms to match the definitions provided is:
- Formal region - an area on Earth’s surface defined by relatively unchanging cultural or physical traits, often associated with a formal boundary.
- Functional region - an area on Earth’s surface defined by one or more linkages and activities occurring in that area.
- Perceptual region - an area on Earth’s surface with boundaries that are based on an individual’s perception, thoughts, and/or knowledge of people and their cultural traits, physical geography, and/or the built environment.
So the correct response is:
formal region, functional region, perceptual region.