: Why did the Greeks develop independent city-states, and not an empire?

Apex plz i’m almost done if i get this all right

How was rockefeller able to build his monopoly across the oil industry? he found newer and cheaper ways to refine oil, increasing his profits. he confined his business to ohio so he could buy all the refineries there. he bought up oil refineries, cut costs, and reinvested his profits in other refineries. he began to sell kerosene as well as oil, expanding his market.

Which of these constitutional amendments made all people born or naturalized in the united states into citizens of the united states ?