Amir Khusrau was a multifaceted personality known for his contributions in different fields. Option 1 states that he was a Sufi saint. This is correct as Khusrau was deeply involved in Sufism and was considered a mystic poet. Option 2 states that he was a Persian and Hindi writer, and scholar. This is also correct as Khusrau wrote extensively in both Persian and Hindi, and was highly regarded as a scholar. Option 3 states that he was a historian. While Khusrau did document historical events in his writings, he is primarily known for his contributions in literature and music rather than as a historian. Therefore, option 3 is not entirely accurate. Option 4 states that he was all of the above, which is the correct answer as Khusrau was indeed a musician, Sufi saint, and a Persian and Hindi writer, and scholar.