Which of Georgia's regions fits this description: lacks fertile soil, smallest land size, smallest population, TAG corner

Appalachian Plateau

Explanation:

Process of elimination:

NOT Piedmont, since it contains the highest population.

NOT Ridge and Valley, since much much of the land is used for agriculture.

NOT Blue Ridge, since this is a popular tourism destination.

NOT Coastal Plain, since it is the largest geographical region in Georgia.

This leaves only the Appalachian Plateau, which is indeed the smallest geographical region, has the smallest population, lacks fertile soil, and is a part of the TAG corner.