Answer : 4. "Pichwai"
Explanation :

Nathdwara is the most important center of Pushtimarg of vallabhacharya and hence it is also called Vallabh style. The painters of Nathdwara began painting Krishna in the world as the inclination of God. Paintings of Pichwai, that is, painting on cloth, is a distinctive feature of the paintings done in Nathdwara.