The right answer is b. preserve the Union.
Lincoln’s paramount goal in conducting the Civil War was to preserve the Union. Like most northerners, he was more determined to end secession than to end slavery. But the course of the war changed Lincoln’s outlook. During 1862, he decided that the emancipation of slaves in the Confederate states was necessary to win the war. Millions of enslaved laborers were being used to bolster the Rebel war effort.