Considering the axial symmetry of this system, we firstly vertically divide it into two equal parts, and discuss the left one.
Clearly, there is a left-horizontal fore
exerts on the half-cube, to keep the half-system balanced,
is equal to the friction comes from the floor, which is right toward.
Let the force between the half-cube and the left-wedge be
, which is perpendicular to the interface, to be balanced we have:
For static fraction we need:
, combining the equations above, we have:
Thus we get, if
, this inequality is naturally assured, there is no constraint on the value of
, we get the answer "D"