The correct answer is: A.
Plessy v. Ferguson was a landmark decision enacted by the US Supreme Court in 1896. It stated that segregation in public facilities did not violate the Consitution, or the equality rights principles introduced by the Fourteenth and Fifteenth Amendments, as long as such facilities were equal in quality.
In conclusion, Plessy v. Ferguson legitimized segregation practices under the principle: "separate but equal".