For walls more than 6 m in height, thickness of retaining wall at the bottom is equal to 0.4 times the height plus

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

1.	For walls more than 6 m in height, thickness of retaining wall at the bottom is equal to 0.4 times the height plus
A.	10 cm
B.	20 cm
C.	30 cm
D.	40 cm
Answer» D. 40 cm