For walls less than 6 m in height, the thickness of the retaining wall at the bottom is equal to

For walls less than 6 m in height, the thickness of the retaining wall

1.	For walls less than 6 m in height, the thickness of the retaining wall at the bottom is equal to
A.	0.2 times the height
B.	0.3 times the height
C.	0.4 times the height
D.	0.5 times the height
Answer» D. 0.5 times the height