Which one among the following mahajanapadas in ancient India was an oligarchy?

Vajji (also called Vrijji) was a well-known oligarchic (gana-sangha) mahajanapada in ancient India, with its capital at Vaishali. It was a confederation of several clans, including the Licchavis, Videhas, Jnatrikas, and Vajjis themselves. Kosala, Gandhara, and Magadha were monarchies. The Vajji confederation is considered one of the earliest known republics in world history.