A homogeneous gravity retaining wall supporting a cohesionless backfill is shown in the figure. The lateral active earth pressure at the bottom of the wall is $40$ kPa.
The minimum weight of the wall (expressed in kN per m length) required to prevent it from overturning about its toe (Point $\color{Red}{P}$) is
- $120$
- $180$
- $240$
- $360$