All of the following are examples of economic interest groups except:
a. groups concerned with civil liberties, such as the national rifle association
b. labor unions, such as united auto workers
c. professional and trade associations, such as the american bar association
d. individual corporate pacs, such as at& t’s pac

Groups concerned with civil liberties such as the National rifle Association.

National Rifle Association is America's non-profit organisation. Founded in 1871, this organisation advocates for gun rights. Since this has been formed to advocate against a single issue, this is a type of single issue organisation. Hence this can't be classified as an economic interest group.