Final answer:
Soil Types A, B, and C are generally ranked in descending order of stability, with Type A being the most stable. The A horizon of soil is the topsoil important for plant production, and the B horizon is the subsoil.
Step-by-step explanation:
When considering the stability of different soil types, they are typically ranked based on how well they can support structures and their resistance to erosion or other geotechnical failures. Based on this, soils would generally be ranked in descending stability from Type A to Type C. Type A soils, found in tropical or equatorial climates, tend to be more stable due to dense vegetation and roots which bind the soil. Type B soils, found in dry or arid climates, have less organic content and moisture, often leading to lower stability. Type C soils, in moderate or temperate climates, may have varying levels of stability depending on local conditions, but they are typically less stable than Type A soils and potentially more stable than Type B soils.
Soil Horizons and Plant Production
Regarding the soil horizons, the A horizon is considered the topsoil, which is vital for plant production due to its rich organic material content. The B horizon is considered the subsoil, accumulating fine material that moves down from the A horizon and resulting in a denser layer within the soil profile.