The answer is slavery. The Republicans were anti-slavery, while the democratic south was pro slavery. Eventually that, and a couple of other things, led to the Civil War.
Sorry if this was a bit late, Brainly had just recommended this question for me to answer, but I hope this helps!
Answer:
Abraham Lincoln, Warren G. Harding, Franklin D. Roosevelt
Explanation:
I believe it would be B polis
A. The Russo-Japanese War.
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