Which of these phrases best describes a uniting principle of the Progressive Era? The answer is in the picture

polisit can also mean a body of citizens. in modern historiography, polis is normally used to indicate the ancient greek city-states, like classical athens and its contemporaries, and thus is often translated as "city-state". the body of citizens came to be the most important meaning of the term polis in ancient greece.

collect the tariff by force if necessary

use the military to enforce a federal law

b and c