Concept:Capillarity is the ability of a soil to draw water upward through tiny spaces between particles.
Soils with finer particles and smaller pores show higher capillary action.
Explanation:Silt and clay particles are very small and fine compared with sand particles.
Small particles leave narrower pores or capillary spaces between them.
Narrow pores create stronger capillary force, pulling water upward more effectively.
Sand has large particles and large pores, so it drains quickly and has low capillarity.
Loam is a mixture with moderate properties, not the highest capillarity.
Among the given options, silt and clay both have fine textures and tiny pores, giving the highest capillarity.
Therefore, a soil containing silt and clay retains water by capillary action very well.
Answer:The correct option is D. silt and clay.