The Pivotal Event That Essentially Crippled Organized Labor Throughout the 1920s

The pivotal event that essentially crippled organized labor throughout the 1920s was

A) the Supreme Court's ruling against the union closed shop in the Adkins case.
B) the deportation of the most effective labor organizers to the Communist Soviet Union.
C) the split within the American labor movement between the American Federation of Labor and the Socialists.
D) the federal government's antilabor intervention that broke the 1919 steel strike.
E) repeal of the Clayton Act guaranteeing unions the right to organize.