Athens kept any one person from gaining too much power by

ostracizing citizens who gained too much power.
having all citizens serve in the assembly.
all of the choices are correct.
having important positions chosen by lot.

Athenian democracy is the pure and direct democracy practiced during the Roman Civilization. People were given the supreme authority to cast vote and elect their king and ministers. Democracy originated from Roman Civilization.

It has its own drawbacks as it involves the people’ emotions directly. Sometimes this form of Government allowed people to take bad decisions based on their emotional instability. It paved way for vengeance and covetousness too.

Athenians refrained one person from getting too much power by keeping constant check on the offices and a council was formed on the basis of lot system which kept a thorough scrutiny on the person who was to become tyrannical, this constant check prevented one from gaining much power.

b.

jim crow laws were enacted in northern states.