What Factor Contributed to the Growth of Union Membership in the 1930s

What factor contributed to the growth of union membership in the 1930s?

A) workers' militancy and the tactical skills of a new generation of leaders
B) the government's unsympathetic view of workers' rights
C) the minimal amount of labor unrest during the 1930s
D) the American Federation of Labor's willingness to organize unions of industrial workers
E) the United Auto Workers' opposition to sit-down strikes