What Was the Purpose Behind Plato's Creation of the Republic

What was the purpose behind Plato's creation of The Republic?

A) He wanted to create a model city-state where democracy allowed the participation of all citizens in the government.
B) He described his vision of a perfect city ruled by an oligarchy.
C) He thought that if humans would imitate his model, the Greek cities would be less susceptible to the decline that he saw in his own time.
D) He hoped that he could achieve a wider audience by having Euripides turn the dialogue into a drama.