Which of the following is a musical instrument that consists of a set of glass, metal or clay bowls, each having varying levels of water?

The correct option is Jaltarang.

The Jaltarang (also spelled Jal Tarang) is a traditional Indian percussion instrument. The name is derived from the Sanskrit words jal, meaning "water", and tarang, meaning "waves".

It consists of a set of ceramic, glass, metal, or clay bowls of tuned sizes. These bowls are filled with varying levels of water to tune them to different pitches. When the edges of the bowls are struck with wooden sticks or beaters, they produce melodic, bell-like sounds. The pitch of each bowl is adjusted by increasing or decreasing the quantity of water inside it: bowls with more water produce a lower frequency (lower pitch), while bowls with less water or smaller sizes produce a higher frequency (higher pitch).

Here is a brief look at the other options to understand why they do not match the description:
- Sitar: A plucked stringed instrument used mainly in Hindustani classical music.
- Shehnai: A double-reed oboe-like wind instrument made of wood and metal.
- Sarod: A plucked stringed instrument known for a deep, weighty, introspective sound.