In counterfort retaining walls, the main reinforcement in the stem at support is A. Not provided B. Provided only on inner face C. Provided only on front face D. Provided both on inner and front faces

The correct answer is: D. Provided both on inner and front faces.

Counterfort retaining walls are a type of retaining wall that uses vertical concrete slabs (counterforts) to support the weight of the soil. The main reinforcement in the stem at support is provided both on the inner and front faces to resist the bending moment and shear force at the support.

Option A is incorrect because the main reinforcement is always provided in the stem at support. Option B is incorrect because the main reinforcement is not only provided on the inner face, but also on the front face. Option C is incorrect because the main reinforcement is not only provided on the front face, but also on the inner face.