Which types of soils include sand, dust, and hair?

The correct choice identifies insoluble soils as the category that includes materials such as sand, dust, and hair. These types of soils are characterized by their inability to dissolve in water or other solvents, which means they remain solid particles. When cleaning carpets, knowing that these soils do not break down easily helps technicians select appropriate cleaning methods and products, such as vacuums or agitation techniques, tailored specifically to effectively remove particulate matter.

In contrast, soluble soils would consist of contaminants that can dissolve in water, like sugar or salt, while organic soils are typically made up of carbon-based substances such as food residues, oils, and greases. Biodegradable soils refer to substances that can be broken down by microorganisms, and this isn't applicable to materials like sand and dust. Understanding these distinctions is crucial for effective carpet cleaning and maintenance strategies.