Answer:
Explanation:
It cannot be C as Russia actually suffered the most casualities due to their poor military capabilities.
It cannot be A as the Allied Powers had more casualties.
It cannot be D as Britain and France combined had more casualties.
It has to be B as Austria-Hungary did lose more casualties than France.
I believe the answer would be cotton gin because the invention of the cotton gin was able to become more efficient in harvesting cotton.
Hey are all living glad to help