Answer : 4. "सवाईमाधोपुर"
Explanation :

1. In the process of unification of Rajasthan, "Matsya Sangh" was first formed on 18 March 1948 by including the princely states of Alwar, Bharatpur, Dholpur and Karauli and Chief Area Neemrana.

2. Matsya Sangh inaugurated by N. It was done by V. Gadgil.

3. On the advice of Kanhaiyalal Manakchand Munshi, this union was named Matsya Sangh.

4. Udaybhan Singh of Dholpur was made the Rajpramukh and Shobharam Kumawat of Alwar was made the Prime Minister.

5. Alwar was made the capital.