Which of the following was a consequence of western expansion in the 19th century?
a. It challenged the power of the North and South because of gold.
b. It contributed to a decline in slavery since it promoted the immigration of poor laborers who would work for cheap.
c. It led to an imbalance of power between the North and the South in Congress by the 1810s.
d. It contributed to the coming of the Civil War because it prompted a debate over slavery.