A person(s) who posed a threat to Southerners because of their combined efforts to end slavery in the United States *

1. Immigrants
2. Abolitionists
3. Slaves
4. Free Labor

Abolitionists

Explanation: Because abolitionists were people who hated slavery and wanted it to end. They did a lot of different things to try to stop slavery.

the fact that could also be added to column b is that during world war ii, specifically between the years 1941 and 1945, japan expanded its territory towards the indonesian territory in what was known later as part of the "pacific war". in that time, japan could conquer the philipines, singapore,   borneo, central java, malang, cebu, sumatra and various other islands of the area, therefore expanding its territory for a brief period of time.