Option 1 -> Thumri is a semi-classical vocal form of Hindustani music with romantic and devotional themes.
Option 2 -> Dhrupad is one of the oldest and most austere forms of Hindustani classical music.
Option 3 -> Khayal is the most popular form of Hindustani classical vocal music, known for its improvisational nature.
Option 4 -> Sattriya is a classical dance form from Assam, originating from monastery traditions, not a form of Hindustani music.
Hence, Option 4: Sattriya -> Sattriya is one of the eight classical dance forms of India, developed in the Vaishnavite monasteries of Assam. While Thumri, Dhrupad, and Khayal are all vocal/musical forms within the Hindustani classical music tradition, Sattriya belongs to the realm of classical dance, making it the odd one out -> correct