Explanation:

- Option 1: Vatsa

- Vatsa was not a confederacy but a monarchical state.

- It was known for its capital, Kausambi.

- Option 2: Magadha

- Magadha was also a monarchical kingdom.

- It became a powerful and influential kingdom in ancient India.

- Option 3: Vajji

- Vajji was a confederacy of eight republican clans.

- It included famous clans like the Licchavis.

- Option 4: Malla

- Malla was a republic but not a confederacy of multiple clans.

- It later came under the influence of larger powers like Magadha.