Ustad Bismillah Khan is best known for playing which of the following instruments?

Shehnai

The correct answer is Option (4) → Shehnai

Ustad Bismillah Khan is best known for playing the shehnai. The shehnai is a reeded woodwind instrument, similar to an oboe, that is particularly important in North Indian music. Khan's virtuosity and expressive playing helped to elevate the shehnai's status and bring it to a wider audience.