Answer:
Fourteenth
Step-by-step explanation:
The Thirteenth Amendment ended slavery. The next step was to make former slaves citizens. I know this isn't a math class, but I'm betting you know what comes after 13. That's right! It was the Fourteenth Amendment that extended the rights of citizenship to former slaves and anyone else born or naturalized in the U.S.
I got it right on my test too.
(Sorry I'm Late!)