Which of these innovations led to increased production in american factories in the early 1800s?
the invention of the mechanical reaper
the use of interchangeable parts
the availability of electricity
the construction of canals

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.

can't without checkbox

1. it was caused by feudalism

2. charlemagne used christianity as a major cornerstone for his rule. cloisters were built all over the empire to act as centers for the (re)population of the vast european wilderness.

3. the europeans feared the next raid every time chetak

i'm not so sure about #6. but i hope i you with the first 3.