ANS:D - None of these.

1. "In the stem of a retaining wall, reinforcement is provided near the earth side." Explanation: The stem of a retaining wall is the vertical portion that rises above the ground surface and retains the soil or other material. In many cases, especially for reinforced concrete retaining walls, reinforcement is indeed provided near the earth side, which is the side facing the retained soil. This reinforcement helps to resist the lateral earth pressure exerted by the soil against the wall. By placing reinforcement near the earth side, the wall can better withstand these pressures and remain stable over time.
2. "In the toe slab of a retaining wall, reinforcement is provided at the bottom of the slab." Explanation: The toe slab of a retaining wall is the horizontal portion at the base of the wall, extending outward from the stem into the retained soil. To enhance the structural integrity of the toe slab and prevent cracking due to bending moments, reinforcement is typically provided at the bottom of the slab. This reinforcement helps to resist tensile forces that may develop in the bottom portion of the slab, especially under loading conditions or due to soil pressure. By placing reinforcement at the bottom, the toe slab can better distribute loads and remain durable.
3. "In the heel slab of a retaining wall, reinforcement is provided at the top of the slab." Explanation: The heel slab of a retaining wall is the part of the footing that extends backward from the base of the stem, providing additional support and stability. Typically, reinforcement is provided at the bottom of the heel slab, not at the top. This reinforcement helps to resist tensile forces and prevent cracking due to bending moments. By reinforcing the bottom portion of the heel slab, the wall can better distribute loads and resist soil pressures effectively.
4. "None of these." Explanation: This option implies that none of the statements provided are incorrect. However, upon closer examination, we can see that statement 3, regarding the placement of reinforcement in the heel slab, is incorrect as explained above.