Please help
best answer = brainlist

Which of the following factors would be a likely reason for low population density

What is zinn's approach to the study of history? what does he suggest occurs when history is told is the story of human progress?

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.