Answer:
D. Abbasid dynasty
Explanation:
The city was founded in 762 as the capital of the ʿAbbāsid dynasty of caliphs, and for the next 500 years it was the most significant cultural centre of Arab and Islamic civilization and one of the greatest cities of the world. It was conquered by the Mongol leader Hülegü in 1258, after which its importance waned.
