With which instrument is Ustad Sultan Khan associated?

The correct answer is Option (4) - Sarangi

Ustad Sultan Khan was associated with the Sarangi.

The Sarangi is a bowed stringed instrument with a skin-covered resonator. It is often used in Indian classical music, and is known for its expressive and soulful sound.

Ustad Sultan Khan was a master of the Sarangi, and was known for his virtuosic playing and his ability to create a wide range of emotions through his music. He was also a pioneer in bringing the Sarangi to a wider audience, and his work helped to popularize the instrument around the world.