I think your question means how did the discovery of gold contribute to the creation of the transcontinental railroad. There had been some movements toward westward settlement in the 1840s, but that trend accelerated dramatically with the discovery of gold in California. James Marshall's finding of gold at Sutter's Mill in California in 1848 led to a "gold rush" in the decade that followed, with 1849 seeing a huge influx of people to California. (Thus we refer to the '49ers.) The swift settlement of California added incentive to build a transcontinental railway. The Pacific Railroad Act of 1862 established the charter for doing that. The First Transcontinental Railroad was completed in 1869.
Answer:
1. The United States is in the Western Hemisphere (because it is west of the prime meridian) and also in the Northern Hemisphere (because it is north of the equator).
Andrew Jackson worried that annexing (aka adding) Texas to the US would divide the nation because Texas would enter the Union as a slave state. During the early to mid 19th century, US presidents were constantly trying to balance the number of free and slave states. Their reasoning behind this is that they did not want any side (aka free states or slave states) gaining too much power in Congress.
During this time, Northern politicians were worried that having a lot of slave states in Congress would result in the slave states making slavery legal in all of the new territories gained by the US during the 19th century. The Southern politicians were worried that if free states controlled Congress, they would try to make a law/amendment to get rid of slavery.
D is the answer ( for cutting off our trade with parts of the world )