The Great plains, not sure why honestly.
Answer:The United States enters World War 1
Invention of the cotton gin
The steps taken by
Incas to unite the empire in the given options are:<span>
1) They built a vast network of roads, bridges, and tunnels.
2) They imposed their language and religion on conquered peoples.
These factors helped them empire unification. Incas are known to have risen as
the strongest Andean Civilization.</span>