Which of the following soils typically has the highest cohesiveness?

Clay typically has the highest cohesiveness among soil types due to its unique particle structure and the presence of water molecules that can bond to its particles. The microscopic size of clay particles allows them to come into close contact with each other, resulting in strong intermolecular forces. These forces, combined with the plate-like shape of clay particles, create a condition where they can easily stick together, making the soil cohesive.

In comparison, other soil types like sand, silt, and gravel exhibit lower cohesiveness. Sand is composed of larger particles that do not bond well, while silt, though finer than sand, lacks the significant electrochemical properties that enhance the cohesiveness found in clay. Gravel, being larger and more angular, also does not exhibit the same cohesive qualities as clay, often relying more on friction between particles. Thus, clay stands out as the soil with the highest cohesiveness due to its fine particle size and ability to retain water and form strong bonds.