I believe it is the last option... "Its political system cannot be easily changed.
It granted citizenship and equal civil and legal rights to African Americans and slaves who had been emancipated after the American Civil War
Segregation and Jim Crow as well as other constitutional measures
Naturalized citizens are mostly more politically involved and tend to participate in things like voting more. Naturalization has a positive effect on voter turnout. Naturalized citizens are often immigrants from areas where their rights are not respected so they move to other places where they are willing to participate in public affairs because the system suits them better.
That the constitution is important