Labor unions of today share characteristics with associations known as

a. merchant guilds.

b. helots.

c. satraps.

d. craft guilds.

Hello! The labor unions share characteristics with associations of artisans and merchants that we can call "guild". In the medieval times, this kind of corporation was common, and was usefull to tha formation of new professionals. We can see one example of the importance of the guilds when we look at the history of the universities, based on the old guilds. Letter d) craft guilds.