The correct answer is option C, Vajji.

The Vajji Mahajanapada was known for its confederation of clans, including Licchhavis and Vedehans. Let's explore this in detail:

1. Vajji Mahajanapada:
The Vajji Mahajanapada was one of the sixteen Mahajanapadas (great kingdoms or republics) that existed in ancient India during the 6th century BCE. It was located in the northern part of present-day Bihar and extended up to Nepal.

2. Confederation of Clans:
The Vajji Mahajanapada was unique among the Mahajanapadas as it was a confederation of several clans. The confederation included the Licchhavis and Vedehans clans, among others. These clans were independent and self-governing units within the confederation, with their own administrative and political systems.

3. Licchhavis Clan:
The Licchhavis clan was one of the most prominent and powerful clans within the Vajji Mahajanapada. They were known for their democratic governance and played a significant role in the political affairs of the region. The Licchhavis had their capital city at Vaishali, which was a prosperous and important center of trade.

4. Vedehans Clan:
The Vedehans clan was another influential clan within the Vajji Mahajanapada. They were also known for their democratic system of governance. The Vedehans clan had their capital city at Mithila, which is present-day Janakpur in Nepal.

5. Political Structure:
The Vajji Mahajanapada had a unique political structure based on a confederation of clans. The confederation was governed by a council known as the Vajjian Sangha. This council consisted of representatives from various clans, including the Licchhavis and Vedehans. The council made important decisions collectively and followed a republican form of government.

6. Importance:
The Vajji Mahajanapada, with its confederation of clans, was known for its political stability, participatory governance, and democratic ideals. It had a strong military and played a significant role in shaping the political landscape of ancient India. The Vajji Mahajanapada's influence extended to neighboring regions, and it was regarded as one of the most powerful Mahajanapadas during that time.

In conclusion, the Vajji Mahajanapada was known for its confederation of clans, including the Licchhavis and Vedehans. This confederation had a unique political structure and played a crucial role in shaping the political landscape of ancient India.