The correct options are
A Death of Harun-Al-Rashid
B Invasion by the Seljuq Turks
After Harun-al-Rashid's death, the Arab kingdom slowly started disintegrating. Independent kingdoms started rising all over the empire. The Caliph, once the overlord of the entire Islamic world, started becoming insignificant day-by-day. When the empire was in such disarray, the Seljuq Turks struck the final blow to the Abbasids by conquering Baghdad.