The correct response is: "American political thought expanded to give Black Americans privileges of U.S. citizenship in the period after the Civil War."
These amendments, often referred to as the Reconstruction Amendments, were designed to address the legal status and rights of formerly enslaved individuals and to ensure their citizenship and voting rights in the aftermath of the Civil War. The Thirteenth Amendment abolished slavery, the Fourteenth Amendment granted citizenship and equal protection under the law, and the Fifteenth Amendment prohibited denying the right to vote based on race.