Concept:There are two famous books titled "The Art of War" — one by Sun Tzu and another by Niccolò Machiavelli. Since Sun Tzu is not among the given options, the correct author from the list is Machiavelli.
Explanation:Sun Tzu wrote the most widely known version around the 5th century BC, but he is not an option here.
Niccolò Machiavelli, the Renaissance political philosopher, published his own "The Art of War" (Dell'arte della guerra) in 1521. This is the only major historical work he published during his lifetime.
In it, Machiavelli discusses the link between military organization and state stability, and argues for citizen armies instead of mercenaries.
The other options are incorrect: Thucydides wrote "History of the Peloponnesian War", Thomas Hobbes wrote "Leviathan", and J.S. Mill wrote "On Liberty".
Therefore, among the given choices, Machiavelli is the correct answer.
Answer:Option A – Niccolò Machiavelli