What improvement in manufacturing did eli whitney popularize?

question 4 options:

interchangeable parts

the moving assembly line

mechanization

the steam engine

answer: d. an organization that fought for women's voting rights

"germany's geographic location was an advantage when it was on the offensive in the war because it was situated next to an extremely wide river, the rhine, which was difficult for the allies to cross."

where is thing if you show me on the map or have a map i can answer your question