Final answer:
The correct option: d. ILO.
The most active international union organization is the ILO, as the AFL-CIO's influence is primarily within the United States, representing over 10 million workers from various unions. The ILO is a global United Nations agency working to promote decent work across its 187 member states.
Step-by-step explanation:
The most active international union organization is the: d. ILO.
The AFL-CIO, while significant, is chiefly a national federation of labor unions in the United States. The AFL-CIO was created by the 1955 merger of the American Federation of Labor and Congress of Industrial Organizations and represents over 10 million workers from more than fifty different unions. The unions within the AFL-CIO, such as the National Education Association (NEA), Service Employees International Union (SEIU), and American Federation of Teachers (AFT), indicate its strong presence nationally.
However, when considering international activity and influence, the International Labour Organization (ILO) stands out as it is a United Nations agency dealing with labor issues on a global scale, involving governments, employers, and workers from its 187 member states to set labor standards and develop policies and programs promoting decent work for all.