To answer your question accurately regarding the regions inhabited by the Mound Builders, I'd need to see the specific map you are referring to. However, based on the description provided, the Mound Builders primarily lived in the area that spans from the Great Lakes to the Gulf of Mexico and from the Mississippi River to the Appalachian Mountains.
If you can provide details about the regions labeled (A, B, C, D, E) on the map, I could help identify which one (or more) corresponds with the Mound Builders' territory. Generally, you would be looking for a region that encompasses parts of the southeastern and midwestern United States.