A cube of side $a$ is placed on rough surface (shown in the figure). Then:
(a) if $f<\frac{M g}{2}$, then the body will move in pure rotation and will not topple
(b) if $F>\frac{M g}{2}$, the body will topple
(c) if $\mu>0.5$, the body will move by toppling
(d) all the above