Final answer:
Vertisols are the soil order characterized by soils high in shrink/swell clays, such as montmorillonite. These clay-rich soils expand when wet and shrink when dry, causing significant changes in volume. They are commonly found in areas with distinct wet and dry seasons.
Step-by-step explanation:
The soil order that is characterized by soils high in shrink/swell clays, such as montmorillonite, is d) Vertisols.Vertisols are primarily composed of clay-rich soils that have a high shrink/swell capacity. These soils expand when wet and shrink when dry, causing significant changes in volume. Montmorillonite is a type of clay mineral that exhibits these characteristics, making it a characteristic feature of Vertisols.For example, when these soils are wet, they become sticky and can form deep cracks upon drying. They are commonly found in areas with distinct wet and dry seasons, like certain parts of the United States, India, and Australia.