Final answer:
The three Reconstruction amendments (Thirteenth, Fourteenth, and Fifteenth Amendments) protected civil rights and liberties.
Step-by-step explanation:
The common trait of the three Reconstruction amendments (Thirteenth, Fourteenth, and Fifteenth Amendments) is that they protected civil rights and liberties. These amendments were passed during the Reconstruction Era after the Civil War and aimed to secure the rights of freed men and women, particularly African Americans. The Fourteenth Amendment, for example, guaranteed equal protection under the law and ensured that states would respect the civil liberties of freed people. The Fifteenth Amendment protected the right to vote for Black men.