What characterizes a saturated soil?

A saturated soil is characterized by its voids being completely filled with water. This occurs when the water table is at or above the level of the soil layer being considered, causing all the pores between soil particles to be occupied by water. This condition significantly affects various physical properties of the soil, such as its strength, compressibility, and permeability.

In contrast, other options describe different soil conditions. A soil with a high void ratio may not necessarily be saturated, as it could contain air in its voids. A dry soil is one where the voids contain air instead of water, indicating that it does not meet the definition of saturation. Low permeability refers to the soil’s ability to transmit water, but does not directly define saturation; a soil can be saturated and still have varying levels of permeability. Thus, option B accurately captures the essence of what it means for soil to be saturated.