Why Did It Take Four Rulings by the U

Why did it take four rulings by the U.S.Supreme Court to bring an end to the white primary?

A) The president used executive order to overturn the first three rulings.
B) The first three rulings were later declared invalid as a result of mistrials.
C) Texas state courts repeatedly overturned the rulings of the U.S. Supreme Court.
D) The Texas legislature and parties kept finding ways to circumvent the Supreme Court's rulings.
E) Only under threat of imposing martial law in the fourth ruling could the Supreme Court enforce it.