Organizations of workers that seek to defend and promote their members' interests are called:

A) team management
B) quality circles
C) unions
D) internal labor markets
E) codetermination

Unions are organizations of workers that represent and advocate for the interests of their members, including negotiating for wages and benefits, improving working conditions, and protecting workers' rights. The other options (team management, quality circles, internal labor markets, codetermination) refer to different approaches to organizing work or decision-making within companies, rather than advocacy for workers' interests.