Despite the fact that conversions to Islam were at their peak, Abbasid power declined because

empire's becoming too big to rule effectively.

Explanation:

While a lot of internal factors have been identified as the cause of the decline of the Abbasid empire. The underlying cause of the decline of the Abbasid empire even though conversions to Islam were at their peak, is understood to be that "empire's becoming too big to rule effectively."

Hence, a lot of internal issues such as civil wars, the Zanj and Qarmatian uprisings, political interference by the Turkish soldiers could not be controlled. And ultimately led to the decline of the empire.

b. she founded a new dynasty that ruled egypt for generations.