The answer to the question would be letter D. The term that defines emigration would be when people leave and no longer live in a country. It does not mesn when people enter another country to love. It is also does not mean the movement of people trom one area to other.
1862: The Civil War is at its height… North and South locked in a bitter conflict for the future of America. A new kind of bullet has brought this war to a terrible deadlock, bringing death on a scale never previously seen before the war. ... The bullet known as the "minie ball."
This is an example of social comparison theory.