What was the result of the japan's invasion of korea int he 1500's

How did the completion of the transcontinental railroad change the lives of american citizens? a-it increased the wealth of all americans and enabled them to travel more.b-it made cross-country travel too expensive for ordinary americans.c-it decreased the safety of americans who moved to settle the plains.d-it shortened travel time between the east and west for all americans.

How does the existence of a site like catus hill demonstrate the challenge that archaeologist face when making theories?

How could the issue of wether to allow slavery in a territory to be decided, using the idea of popular sovereignty?