According to the ruling in the Plessy v. Ferguson case (1896), segregation was deemed acceptable under the doctrine of "separate but equal." The Court concluded that racial segregation was constitutional as long as the separate facilities for blacks and whites were equal in quality. This ruling provided a legal basis for racial segregation in public facilities, which persisted for many decades until it was overturned by later court decisions, notably Brown v. Board of Education in 1954. Therefore, the correct answer is:
Segregation was legal as long as the facilities for black and whites were equal.