Which Two of the Following Administrative Approaches Have Presidents Used

Which two of the following administrative approaches have presidents used to staff the White House?

A) the model of a wheel on which each spoke, each key staffer, leads directly to the president
B) the model of concentric circles on which staffer authority increases inversely to the circumference of the circle
C) a hierarchical staff design in which lines of authority and reporting are clear
D) a democratic staff design in which lines of authority overlap and are collaborative