The correct answer is C) Plato.
The Republic was written by Plato.
We are talking about one of the most important works of the Greek philosopher Plato and one of the most influential books in modern politics.
The main character of "The Republic" is Socrates. In the book, Socrates defends his argument of how important is justice to have a happy life. He first explains the concept of justice and then proceeds to argue if the just individual is happier than the unjust individual.
The other options of the question were A) Confucious. B) Aristotle. D) Socrates.