Let H= height of retaining wall, ϒ=unit weight of backfill and ka = coefficient of active earth pressure, kp = coefficient of passive earth pressure, then bending moment at any height ‘h’ below top of the wall is given by

• A. pa = ka ϒ h
• B. pa = kp ϒ h
• C. pa = ka ϒ h2 /2
• D. pa = ka ϒ h3 /6