The correct answer is D. Bansuri.
The bansuri is a long, thin, wooden flute that is traditionally associated with Lord Krishna. It is said that Krishna loved to play the bansuri, and that his music would often soothe the animals and people of Vrindavan. The bansuri is still played today in many parts of India, and it is considered to be a sacred instrument.
The shankh is a conch shell that is often used in Hindu religious ceremonies. It is said that the sound of the shankh can awaken the soul and bring peace to the mind. The shehnai is a wind instrument that is often used in Indian classical music. It is a long, narrow instrument with a double reed. The been is a stringed instrument that is similar to a sitar. It has a long neck and a gourd body.
All of these instruments are beautiful and have their own unique sound. However, the bansuri is the instrument that is most closely associated with Lord Krishna.