If H is the overall height of a retaining wall retaining a surcharge, the width of the base slab usually provided, is

ANS:E - 0.7 H

In standard engineering practice, the width of the base slab for a retaining wall is commonly designed to be around 0.5 times the overall height of the wall (0.5H). This dimension helps distribute the loads from the wall and the retained soil effectively, providing stability and preventing excessive settlement or overturning. Therefore, the correct width of the base slab for a retaining wall is usually considered to be approximately 0.5 times the overall height of the wall (0.5H), not 0.7 times the height.