The correct response is:
President Lincoln only had the authority to ban slavery in the Confederacy, not the Union.
The Emancipation Proclamation was issued under Lincoln's war powers as president, which allowed him to free enslaved people in the Confederate states that were in rebellion against the Union. However, he did not have the authority to abolish slavery in the border states or other areas that were loyal to the Union, which continued to have laws regarding slavery at that time.