Final answer:
The Thirteenth Amendment, passed in 1865, abolished slavery throughout the Union, signaling the end of this institution in the United States.
Step-by-step explanation:
The Thirteenth Amendment
Passed in 1865, the Thirteenth Amendment played a crucial role in shaping the future of the United States after the Civil War. The correct answer to the student's question is Option b: The Thirteenth Amendment abolished slavery throughout the Union. This momentous amendment legalized the eradication not only of slavery but of all "badges of servitude", empowering Congress with the authority to enforce it with appropriate legislation. This move was a significant step towards ensuring freedom for approximately four million people and set the foundation for subsequent amendments that aimed to protect the rights of the newly freed individuals.
In contrast, the Fourteenth Amendment defined U.S. citizenship and granted equal protection under the law, while the Fifteenth Amendment secured voting rights for Black men. Neither of these amendments are the subject of the question.