Which musical instrument was invented by the poet Amir Khusrau?

Sitar

The correct answer is Option 3- Sitar

Khusrau is credited for the invention of the sitar. At the time, there were many versions of the Veena in India. He rechristened the 3 stringed Tritantri Veena as a Setar (Persian for 3 stringed), which eventually became known as the sitar.