In which case did the Supreme Court rule that segregation was constitutional?

The Supreme Court ruled that segregation was constitutional in the case of Plessy v. Ferguson. This landmark decision from 1896 established the "separate but equal" doctrine, which upheld state laws requiring racial segregation in public facilities. The Court's ruling was based on the argument that as long as the separate facilities for different races were equal, segregation did not violate the Equal Protection Clause of the Fourteenth Amendment. This ruling effectively provided legal justification for the continuation of racial segregation for many years until it was eventually overturned by Brown v. Board of Education in 1954. The cases listed in the other choices do not pertain to the legality of segregation; they address different aspects of constitutional law and civil rights.