Option a is the correct answer. Amir Khusrau (1253-1325) was a Persian poet, musician, scholar, and mystic who lived in Delhi during the Delhi Sultanate period. He is regarded as the "father of Urdu literature" and the "father of Qawwali" (a form of Sufi devotional music). He wrote poetry in various languages, including Persian, Arabic, Hindi, and Braj Bhasha, but he was the first to use Urdu (or Hindavi, as it was then called) as the medium of poetic expression. Amir Khusrau was a disciple of the famous Sufi saint Nizamuddin Auliya, and expressed his love and devotion for him in many of his poems. He also participated in the cultural and political life of Delhi, serving as a court poet and adviser to several sultans and nobles.