Answer:
Option: The process that America underwent in the late 19th Century that transitioned populations from urban to rural areas.
Explanation:
Industrialization in America changed dramatically after the Civil War. The manufacturing industries set up for the production of textiles, etc. As the industries began to grow in the cities, people from rural areas began to move in cities to find works. The lack of work in rural areas after the Civil War pushing people to move towards the industrial areas where people could earn a living.