How was the system of government of Athens different from the system of government of the United States?

A. Athens had an oligarchy in which several wealthy people ruled the government, while the United States is a republic in which all its citizens take part in government.
B. Athens had an alliance system that gave all members a voice in the government, while the United States has a democratic system that elects officials to make decisions.
C. Athens had an indirect democracy that allowed all citizens to take part in government, while the United States has a direct democracy in which people vote for representatives.
D. Athens had a direct democracy because all citizens took part in government, while the United States has an indirect democracy in which the citizens elect representatives.