What Was the Trend of Urbanization During Much of the Abbasid

What was the trend of urbanization during much of the Abbasid empire?

A) Because the Abbasids abandoned Baghdad for other capitals, cities within the empire tended to wither and die.
B) Successive invasions led to a decline in urbanization.
C) Despite political disintegration and a decline in the agricultural economy, towns continued to grow rapidly.
D) Towns established in the early years of the dynasty were able to hold their own, but there was little growth.