I believe they were extending the revolution through the medium of anti slavery, the strongest Union principle.
I think the answer is D if not the answer should be B
Answer:
Popular Sovereignty
Explanation:
When the representatives are elected to congress, the principle of government that applies is the Popular sovereignty. The principle of popular sovereignty states that the authority and power to create as well as sustain the government lies among the people of the country. It is based on the concept that people are real rulers in a democracy and the elected representatives are servants of people who are the sovereigns.
The thing which was a major factor that threatened the major unity in the United States in the mid-19th century was:
<h3>The Great Depression</h3>
This refers to the period around 1929 in the United States which has a profound effect on the national economy.
This led to the failure of many banks, increase in unemployment and high deflation rates which all threatened the national unity.
Read more about Great Depression here:
brainly.com/question/441267