They used interchangeable parts. This made the mass production possible and caused it to happen.
Answer:
A. Everyone must follow the law
They took the place of men in many war industries
Nationalism and imperialism were major factors to the world war 1. that lead to some conflicts between nations. imperialism also contributed to start world war 1 because the European nations attacking and conquering different areas of Africa and Euro nations attacking other Euro nations for African Territory.