What Was the Consistent Theme of Major Supreme Court Decisions

What was the consistent theme of major Supreme Court decisions in the decades following the Civil War?

A) State governments can do little to use political power to disadvantage black persons.
B) The Constitution requires a broad interpretation of the Thirteenth, Fourteenth, and Fifteenth Amendments.
C) The federal government can do little to affect race relations in the states.
D) The federal government is the only authority on the implementation of the Thirteenth, Fourteenth, and Fifteenth Amendments.
E) The judiciary is supreme over the other branches of government in matters of economic development.