ANS:A - as one third of the base

The toe projection of foundation slabs is typically taken as one third of the base. Here's why:

1. Stability: The toe projection provides additional stability to the foundation by spreading the load over a wider area. This helps prevent overturning and sliding of the foundation.
2. Load Distribution: By extending the foundation beyond the base, the load is distributed over a larger area of soil, reducing the pressure exerted on the ground below.
3. Prevention of Soil Erosion: The toe projection helps to prevent soil erosion around the base of the foundation, particularly in cases where water runoff or other environmental factors could potentially undermine the foundation.
4. Building Codes and Standards: Many building codes and engineering standards specify a minimum toe projection for foundation slabs to ensure adequate stability and load distribution.