Who among the following historical accounts stated that there was no slavery in India?

The Greek ambassador Megasthenes, in his famous book Indica, observed and recorded that all Indians were free and that slavery did not exist in India. This observation likely stemmed from the fact that the harsh, institutionalized form of Greco-Roman slavery he was familiar with was absent in Indian society, causing him to misunderstand the local caste-based labor and dasa systems.