Back fill with a sloping surface exerts a total active pressure Pa on the wall of height H and acts at
(A) H/4 above the base parallel to base
(B) H/2 above the base parallel to base
(C) H/3 above the base parallel to base
(D) H/5 above the base parallel to base
(A) H/4 above the base parallel to base
(B) H/2 above the base parallel to base
(C) H/3 above the base parallel to base
(D) H/5 above the base parallel to base