What Was the "Nuclear Option" Threatened During the Nomination of Supreme

What was the "nuclear option" threatened during the nomination of Supreme Court Justice Alito?

A) The Republicans would disallow the use of the filibuster so that there would be no means for the minority party to protest a nomination.
B) The Democrats would tie up the business of the Senate by not acting on anything requiring unanimous consent.
C) The Democrats would not approve any more justices nominated by President Bush.
D) The Republicans would change the rules so that Supreme Court nominations would no longer be subject to approval by the Senate.
E) The Supreme Court would grow to have two more members so that the president could "pack" the court with conservative judges.