ANS:E - all the above.

• Soil mass is homogeneous, dry, and cohesionless: This assumption implies that the soil behaves as a uniform mass without variation in properties such as density, moisture content, or cohesion. In reality, soils are often heterogeneous, and their properties can vary significantly.
• Ground surface is a plane which may be horizontal or inclined: This assumption simplifies calculations by considering the ground surface as a flat plane. In actuality, ground surfaces are irregular and may have slopes or undulations.
• Back of the wall is vertical and smooth: Rankine's theory assumes that the back of the retaining wall is vertical and free from irregularities or roughness that could affect the pressure distribution. In practice, walls may have various shapes and surface textures.
• Wall yields about the base: This assumption suggests that the retaining wall is rigid and does not deform under the applied earth pressures. In reality, walls may experience deformation or displacement, especially under high loads or in soils with low bearing capacity.