The correct answer would be the denying of rights and privileges to black people, especially voting. This is because disenfranchisement mainly meant the restricting of voting rights (or at least what it mainly meant in the USA), but also is used to describe other rights being restricted.
Here are why the other answers are wrong:
Though the case did lead to segregation being rampant throughout the south, the way the answer is set up makes it incorrect (though it’s technically correct, since it’s taking the right of black people to eat in regular restaurants or use certain services, and many of the “black” facilities were in bad condition).
The definition of disenfranchisement is an antonym of advancements of any rights.
Disenfranchisement doesn’t describe the personal attacks against those groups of people.
Hope this helps!