Why did the Cold War result in an “arms race”?

Which event was one of the causes of the french revolution in 1830?

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.

Where were the trials to review evidence in cases against high-ranking nazi officials accused of war crimes held?