How did lincoln's emancipation proclamation affect slaves during the civil war?

Slaves in the Confederacy were free, but slaves in the border states (i.e. slaves states that did not secede from the Union i.e. Missouri, Kentucky, West Virginia, Maryland, Delaware) remained slaves. This is because Lincoln needed the support of the border states during the Civil War and this transformed the war from a war to keep the country unified to a moral war against slavery. He feared that European countries such as Britain and France would aid the Confederacy because they had good trade relations with the confederate states (which harvested a lot of cotton and other cash crop with the use of slaves). After the Emancipation Proclamation, these counties were discouraged to support the confederacy because they knew they would not have the support of their own citizens who would have felt it would be immoral since these countries had already abolished slavery. He also felt that the Constitution protected the right to own slaves, so he could only free slaves in the rebel states who were no longer subject to the constitution after the secession. The only way to ban slavery was to amend the constitution itself. Slavery in the US was not complete abolished until after the Civil War in the 13th amendment.

Ithink the answer is b : )