The correct answer is separate but equal.
In the Brown vs. Board of Education case, the Brown family (with their lawyer) were arguing that the "separate but equal" facilities for black and white students was a clear violation of the 14th amendment. This was a monumental case, as segregated schools have been part of the US since the Plessy vs. Ferguson ruling in 1896. Ultimately, the Supreme Court justices sided with the Brown family saying that "separate but equal" was a clear violation of the 14th amendment. More specifically, it violated the Equal Protection clause of this amendment.