Which of the following soils is most affected by moisture when drying out?

Fine-grained soils are most affected by moisture when drying out due to their high surface area and the small size of their particles, which allow them to retain water more effectively than coarser materials. As these soils become saturated, they can exhibit significant changes in properties such as cohesion and plasticity.

When fine-grained soils dry out, they can shrink and develop cracks. This behavior is largely due to capillarity and the cohesive forces between water molecules that help hold the soil particles together. With moisture removal, the attraction between the particles decreases, leading to a loss of structural integrity and making the soil more susceptible to changes in physical properties, like increased plasticity or compressibility.

In contrast, coarse-grained soils, like gravel and sand, have larger particle sizes which means much less surface area for moisture retention, making them less affected by changes in water content. Organic soils, though they can retain moisture due to their fibrous nature, primarily change in terms of decomposition and not as significantly in physical stability as fine-grained soils. Cohesive soils generally encompass fine-grained soils, but describing them as cohesive does not specifically emphasize their behavior with moisture loss as effectively as identifying them as fine-grained. Thus, fine-grained soils