Chemical weapons
Both sides developed lethal forms of chemical welfare that resulted to death of thousands in the trench war.Germany was the first to employ chemical weapons and it is estimated that over 10,000 tonnes of chemical gas, lethal and poisonous was blown.
D. maybe but I'm not totally sure. I'm sorry this isn't my best subject, but you can always ask me. I'm always here to help with whatever you need.
I think both Imperial China and Rome were both able to create a strict government. They were able to create a social stratification that allows people to function according to their designated roles, They were able to enforce a strong military which leads to successful conquest of neighboring states.