Answer: b. Grand Prairie
Explanation: The Gulf Coastal Plains are located in Southern USA and are subdivided into 5 regions which are;
The Piney Woods in the east
The Gulf Coast Plain which is to the south of the Piney Woods
The Post Oak Belt which is to the west of the Piney Woods and the Post Oak Belt.
The Blackland Prairie which is west of the Post Oak Belt and,
The South Texas Plain which is to the west of the Gulf Coast Plain as well.
The Grand Prairie is not a region/ section in the Coastal Plains.