How did the people in WWII change or affect the history of the United States?

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.

What was going on with south asia before europeans came ?

What does the term “escalation” refer to?