Explanation:

- The correct answer is: Option:3, Plato.

- Plato, in his famous work "The Republic," classified society into three classes: Guardians (rulers), Auxiliaries (soldiers), and Workers (producers/laborers).

- Simmel was a German sociologist, but he focused on social forms and interaction, not this type of classification.

- Rousseau discussed concepts of social contract and natural state, but did not classify society into these three groups.

- Aristotle did categorize forms of government and functions in society, but he did not use the precise guardians-auxiliaries-workers division.