The correct answer is A) border.
Kentucky, Missouri, Maryland, and Delaware were known as border states.
We are talking about the American Civil War years. During this period, the above-mentioned states remained as part of the Union. They did not secede and became part of the Confederacy, as other southern states did. Kentucky, Missouri, Maryland, and Delaware. Although people from those states could have different opinions regarding slavery, they maintained their loyalty to the Union.
