Which is the oldest surviving form of Hindustani vocal music, austere in style and associated with Tansen?

Explanation

1. 01

   Dhrupad is the oldest surviving form of Hindustani classical singing.

2. 02

   It is deliberately austere, gives a long unmetred alap before the composition, and avoids ornament for its own sake.

3. 03

   Khayal displaced it as the dominant concert form from the eighteenth century onwards.