What type of soil is characterized by high cohesiveness?

Clay soil is characterized by high cohesiveness due to its fine particle size and plate-like structure, which leads to strong particle-to-particle attraction. This cohesiveness enables clay to hold its shape when wet and allows it to conform to molds easily. As the water content changes, clay experiences swelling and shrinkage, further highlighting its plasticity and sticky properties.

In contrast, sandy and granular soils have larger particles that do not adhere to one another, resulting in low cohesiveness and quick drainage capabilities. Silt soil, while finer than sand, still does not possess the same level of cohesion as clay due to its intermediate particle size. Therefore, clay's unique properties make it the soil type with high cohesiveness, distinguishing it from the other options.