In which book did Plato examine the question "what is justice?"

The Republic

The correct answer is Option 2 - The Republic

In his book 'The Republic', Plato examines the question "what is justice?" through the character Socrates and various dialogues.

In ancient Greece, in the city of Athens, Socrates was described as the ‘wisest man’. He was known for questioning and challenging popularly held beliefs about society, religion and politics. For this he was condemned to death by the rulers of Athens. His student Plato wrote extensively about the life and ideas of Socrates. In his book ‘The Republic’, he created the character Socrates and through him examined the question – what is justice? The book opens with a dialogue between Socrates and Cephalus. In the course of this dialogue Cephalus and his friends come to recognise that their understanding of justice is inadequate and unacceptable. The important thing in this is that Socrates uses reason to reveal the limitations and inconsistencies in a given point of view. His adversaries eventually admit that the views they had held and lived by could not be sustained.