Guilds were associations of people from the same industry: artisans and merchants who controlled their field, that is controlled what and how the services could be. They controlled the tools and the procedure of production and services.
The correct answer is:
controlled how their industry operated
The American work force grew in the 1800s because industrialization created new jobs. ... There were no child labor laws, factories needed as many workers as they could get, families needed as much money as they could get, and children had smaller fingers and hands, making them ideal for some more precise jobs.