Which of the following contributes to the wet density of the soil?

Wet density of soil is a measure that takes into account the mass of the soil per unit volume, including all components present in it. The correct answer highlights that solids, liquids, and gas are all integral in determining the wet density.

Solids refer to the mineral particles and organic matter within the soil, which provide the primary structure and weight. Liquids, primarily water, are critical because they occupy the pore spaces between the soil particles, and their presence significantly influences the density. Gases, such as air, also affect the overall density because they occupy some of the void spaces in the soil. When these three components—solids, liquids, and gases—are combined, they contribute to the overall mass and volume of the soil, thereby influencing its wet density.

By understanding that the wet density depends on the combination of all three elements, you gain insight into how soil behaves in different moisture conditions and how it can affect factors such as compaction and stability in construction and earthwork projects.