HI, a frontier is an area of unexplored land close to or near a states borders.
The correct answer is B.
The development of cheap iron in the US was the major factor that lead to the building of skyscrapers. Being able to produce iron cheaply can be contributed to Andrew Carnegie. This American business mogul perfected the Bessemer process in several factories across the eastern part of the US. From there, he was able to sell cheap iron to American businesses for the purpose of growing their empire.
In sum, Stowe's Uncle Tom's Cabin widened the chasm between the North and the South, greatly strengthened Northern abolitionism, and weakened British sympathy for the Southern cause. The most influential novel ever written by an American, it was one of the contributing causes of the Civil War.
One feature that helped the U.S. grow in industry was the inovation.
Answer:
Explanation:
The answer is C to stop the spread of slavery
