As part of the process of readmission to the Union as outlined in the Reconstruction Acts,

The Reconstruction Acts required former Confederate states seeking readmission to organize new governments and adopt new state constitutions that guaranteed voting rights for Black men. The acts also required ratification of the Fourteenth Amendment, not the Thirteenth, which had already abolished slavery. Therefore, the correct choice is “each state had to adopt a new constitution.”

AI-written and checked against the verified answer.