Answer :
The driving question of The Republic is 'What is justice?', which Socrates explores by initially defining political justice in a city-state and then applying it to personal justice. The dialogue evolves into whether a just life leads to greater happiness and fulfillment, indicating that justice is necessary for the maximum possible happiness. Thus, the correct option is b.
The driving question of The Republic by Plato is b) What is justice?. This central question is thoroughly examined in the dialogue, as Socrates engages with various interlocutors to define the concept of justice and to determine whether a life lived justly is inherently happier and more rewarding than one lived unjustly. In the course of the dialogue, Socrates proposes that by understanding justice on a larger scale within a city-state (political justice), one can then apply this understanding to the individual (personal justice).
In Book IV, Socrates concludes the first main question of what justice is by defining it as a matter of psychic harmony, transitioning from the earlier debate on justice's outward behavior. Then, moving towards the Republic's second question, Socrates argues that while justice may not be sufficient for happiness, it is necessary for it, suggesting that the just person, who leads a just life, will experience the maximum happiness possible in their circumstances compared to an unjust person.
Furthermore, the second question of The Republic inquires whether leading a good, just life is correlated with having a good life in the sense of being happier or more fulfilled. The implication being that there is a deeper sense of long-term fulfillment, or eudaimonia, that comes with living justly rather than simply pursuing momentary pleasures.