Q. Which of the following mahajanpada was gana sanghas or oligarchy?
Answer: A
Notes:
Explanation: The proto states of the Gangetic region were known as janapadas and comprised chiefdoms, republics and small kingdoms.
- Sixteen mahajanapadas are mentioned in the early texts. There were also gana sanghas or oligarchies, which were centred on clans.
- The Vrijjis were one of the best known of the gana-sanghas, and Vaishali was their capital in the Mithila region.
Source: Tamil Nadu NCERT

