Conventions are meeting that delegates have one famous convention is the constitutional convention. And if your talking about the fun conventions like the science ones or beauty conventions those are like party anyone is invited to
I never reviewed this in class but I do remember that my teacher said that Rome had a strong army. I know its not B, C, and I don't think its D.
Hopefully this helped you.
The main job is to help the president. Each of them know something different so that means that they help and give the president advice and information.