The main way in which the <span>federal system helps prevent the centralization power is that it reserves a good deal of power for the individual states--meaning that this power "checks" the power of the central (federal) government. </span>
Regional diversity affected the development of Islam because as Islam spread it went to numerous culturally diverse regions. These regions and peoples adopted Islam and developed the religion differently. From regions as wide as West Africa to Indonesia, Islam took on unique forms because of the people who took up the religion and adapted the religion along the way.
I'm thinking B. But could be wrong:/