The correct answer is option 2: Shahnai.

Ustad Bismillah Khan is widely recognized as one of the greatest shahnai players of all time. The shahnai is a traditional Indian wind instrument that is made of wood and has a double reed. It is often played in Hindu wedding ceremonies and other auspicious occasions.

The other options can be eliminated because Ustad Bismillah Khan is not known for playing those instruments. The tabla, for example, is a pair of drums played with the hands, while the sarod is a string instrument and the flute is a wind instrument.

It is important to note that Ustad Bismillah Khan`s contributions to Indian classical music go beyond his mastery of the shahnai. He helped popularize this instrument worldwide and received several prestigious awards and honors in recognition of his talent and cultural contributions.