Daniel JElazar's Argument That the "Virtue of the Federal System Lies

 Daniel J.Elazar's argument that the "virtue of the federal system lies in its ability to develop and maintain mechanisms vital to the perpetuation of the unique combination of governmental strength,political flexibility,and individual liberty which has been the central concern of American politics" means that 

A)  cities and towns can try new things before the rest of the country. 
B)  different states can have different rules for their people. 
C)  state governments can eliminate corruption that the national government cannot. 
D)  different states can regulate their different economies. 
E)  All of these are correct.