Explanation:

- S Balachander was a renowned Indian musician famous for his incredible skill in playing the veena.

- Option 1: Sitar - It's a plucked string instrument used in Hindustani classical music, but not the primary instrument associated with S Balachander.

- Option 2: Veena - This is a traditional string instrument prominent in Indian classical music, and S Balachander was especially acclaimed for his virtuosity with the veena.

- Option 3: Violin - While a key instrument in Indian classical and Western music, it's not S Balachander's claim to fame.

- Option 4: Flute - A wind instrument, popular in both Hindustani and Carnatic music traditions, but not associated with S Balachander.

Option 2: Veena is the correct answer.