What are the events that contributed to the emergence of the us as a world power in the early nineteen hundreds?

Which describes the persian empire? choose all that are (a) the persian army defeated the athenians at the battle of marathon. (b) the persians avoided using ideas from the peoples they conquered. (c) cyrus allowed conquered peoples to keep their cultures. (d) darius i built a network of good roads for communication. choose all that are

The slave dred scott sued for his freedom because he was born a free man. he had lived in a free state. slavery violated the 13th amendment he had been freed by pres. lincoln.

The soviet union and the united states believed in two very different economic systems. what were the names of each?