<em>C. Industrial Revolution.</em>
Explanation:
The combination of resources, improved transportation and technological breakthroughs all led to the Industrial Revolution. This was a huge part of growing America and cultural changes occurred.
The biggest impact the Industrial Revolution had was in the North, as the North was not as focused on agriculture as the South and the West. The North started booming with industries and factories, causing many people from other parts of the United States and even immigrants to try to get jobs.
Many resources and minerals were being found, which helped to fuel factories and transportation. Railroads were starting to be created all over the country, which made selling and buying a lot easier. New technology was being invented, both in the South and the North.
FERA Federal Emergency Relief Administration
A. Transcontinental railroad
Usually, back then, they followed their food and tracked them without settling too long in one place. But since that's not one of the answers I would go with A.
I hope that helps.
