What kind of governance system was seen in some mahajanapadas known as ganas or sanghas?

Oligarchy

The correct answer is Option 3 - Oligarchy

Oligarchy refers to a form of government where power is exercised by a group of men. The Roman Republic, about which you read last year, was an oligarchy in spite of its name.

The sixth century BCE is often regarded as a major turning point in early Indian history. It is an era associated with early states, cities, the growing use of iron, the development of coinage, etc. It also witnessed the growth of diverse systems of thought, including Buddhism and Jainism. Early Buddhist and Jaina texts mention, amongst other things, sixteen states known as mahajanapadas.

While most mahajanapadas were ruled by kings, some, known as ganas or sanghas, were oligarchies, where power was shared by a number of men, often collectively called rajas. Both Mahavira and the Buddha belonged to such ganas. In some instances, as in the case of the Vajji sangha, the rajas probably controlled resources such as land collectively.