Which statement best differentiates between the rust belt region and the rest of the united states?

the rust belt is a perceptual region that is commonly referred to as because of its past prominence as an ecoregion
the rust belt is a functional region characterized by similar historic economic activity, specifically agriculture
the rust belt is a functional region characterized by similar historic economic activity, specifically manufacturing
the rust belt is a formal region surrounded by functional regions

The statement that best differentiates between the rust belt region and the rest of the United States is: "the rust belt is a functional region characterized by similar historic economic activity, specifically manufacturing."