The correct option is: "the use of interchangeable parts"
The interchangeable pieces are part of a basic concept that consists in creating identical or almost identical pieces to be used in a chain production. These pieces can be assembled making a set to form a finished final product. For example, cars, computers, furniture, practically all the products that are used today, are made of interchangeable parts. In the USA Eli Whitney was the first to use interchangeable parts in the manufacture of firearms.
probably something to do with great depression. feel like that's very wrong though
a. there was serious competition for tech jobs at the downtown clinic.
i think that the answer is polishing peanuts