Final answer:
The Emancipation Proclamation, signed by President Lincoln, declared that slaves in Confederate territories were free, shifting the Civil War's focus to ending slavery and allowing African Americans to join the Union Army.
Step-by-step explanation:
The Emancipation Proclamation, issued by President Abraham Lincoln on January 1, 1863, declared that all slaves in Confederate-held territory were free. This announcement did not immediately free all slaves, particularly not those in border states or regions under Union control, but it did change the focus of the Civil War. Initially, the war was fought to preserve the Union. However, the proclamation shifted the war's purpose towards ending slavery and allowed for the recruitment of African Americans into the Union Army, strengthening the Northern warfare effort and making British support for the Confederacy problematic due to Britain's anti-slavery stance.
The correct answer to the question is A) It declared that all slaves were immediately free, shifting the war's focus to ending slavery. However, this should be understood with the nuance that the Emancipation Proclamation had its limitations and primarily applied to states in rebellion against the United States.