Option d is the correct answer. Amir Khusrau emerged as a great musician in the Sultanate period. He invented 'Sitar' with a combination of Irani Tambora and Indian Veena. He combined some Indian and Persian melodies elegantly and introduced some new melody styles like Iman, Zilf, and Sajgari, etc. Thus Sitar is finest example of Hindu-Muslim harmony in musical instruments.