Final answer:
The Ten Percent Plan offered Southerners an official pardon if they swore allegiance to the Union.
Step-by-step explanation:
The Ten Percent Plan, proposed by President Abraham Lincoln in December 1863 during the Reconstruction era after the Civil War, aimed to readmit the Southern states into the Union. Under this plan, Southerners were offered an official pardon if they swore allegiance to the Union. Only 10 percent of the 1860 voting population in the former Confederate states needed to take a binding oath of future allegiance to the United States and emancipation of the enslaved in order for the states to be readmitted to the Union and draft new state constitutions.