An organized labor category is an organization of workers- which means that we can exclude all organisations that do not unite workers: for example the American Rifle Association (unites advocates of gun rights) and the National Audobon Society, which is an environmental organization).
I haven't heard of the National Broadcasting Corporation: do you maybe mean the National Broadcasting Company? Again it's not a labor union, but a media network.
The correct answer is the National Education Association - it unites school teachers and support personnel.
