Which one of the following political interest groups falls into the organized labor category?
a. american rifle association
b. national audubon society
c. national broadcasting corporation
d. national education association

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.