I’m not 100% sure but I think the answer your looking for is that they gained more than 500,000 square miles of land
Answer:
It didn't consider the population sizes of the states
The correct answer is - Great Basin, Rocky Mountain, and Colorado Plateau.
Utah is a state in the United States of America. It is located in the western part of the country. Most o the country is arid and semi-arid, thus making it one of the most inhospitable states in the United States for living, expect for small areas.
Utah's territory is in general divided into three land regions, the Great Basin, Rocky Mountain, and Colorado Plateau.
The Rocky Mountain region is occupying the central part of the state. The Great Basin occupies most of the western part of the state, while the Colorado Plateau occupies the eastern part of the state.