What Was the Supreme Court's Record in Segregation Cases in the Years

What was the Supreme Court's record in segregation cases in the years before Brown v. Board of Education?

A) The justices overturned forms of segregation using the separate but equal rule.
B) The justices had struck down forms of segregation through the commerce clause, not the Fourteenth Amendment.
C) The justices consistently refused to strike down any form of segregation.
D) The justices had already struck down separate but equal as a principle before Brown.
E) The justices had refused to hear cases on segregation before Brown.