The Red River Plains is the region of Oklahoma which is home to the Grand and Illinois rivers. Option C is correct.
The Red River Plain extends in the southeastern region of Oklahoma where you can view large stands of trees and grassy prairies.
The Illinois river is the main affluent of the Mississippi river and it is is formed by the confluence of the Kankakee River and the Des Plaines River in eastern Grundy County.
The Grand River extends in the southwestern area of the southern peninsula of Michigan.