The correct options are
B Vajji was a gana ruled by a group of rulers.
D Ganas were active for over 1500 years.
Vajji was located to the North of Magadha. Unlike Magadha, where one king ruled at a time, Vajji was ruled by a group of kings. This form of government was known as a gana. In ganas, a group of people performed rituals, met in assemblies and decided on issues after debates and discussions. However, women, slaves and wage workers were not allowed to participate in this assembly.