challenge: What was the role of Isma'il ibn Salih ibn Ali al-Hashimi in the Abbasid Caliphate?
  
  A. He was a prominent military leader in the Arab conquests
  B. He was a renowned Islamic scholar and theologian
  C. He was a governor of Egypt and Aleppo
  D. He was the founder of the Abbasid Caliphate
  Answer: 