Which of the following works states that the society was divided into seven classes in the Mauryan period?

Megasthenes' work 'Indica' provides the earliest detailed foreign account of Indian society and specifically mentions the seven-class division during the Mauryan period. As a Greek ambassador to Chandragupta Maurya's court, his observations are primary sources for Mauryan social structure. The Arthashastra deals with statecraft, the Edicts are moral pronouncements, and the Puranas are religious texts - none describe this social stratification.