If a Is the Area of the Foundation of a Retaining

If A is the area of the foundation of a retaining wall carrying a load W and retaining earth of weight w per unit volume, the minimum depth (h) of the foundation from the free surface of the earth, is

A) h = (W/Aw) [(1 - ) /(1 + sin ) ]
B) h = (W/Aw) [(1 + ) /(1 + sin ) ]
C) h = (W/Aw) [(1 - ) /(1 + sin ) ]²
D) h W/Aw) [(1 - ) /(1 + sin ) ]²