Q. Which geographical entity constitutes the layers termed as O Horizon, P Horizon, and A Horizon?
Answer: Soils
Notes: In earth studies, horizons refer to specific layers or strata in soils or rocks. The given terms pertain to three primary horizons of the soil profile that differ in their physical and chemical composition. O Horizon, the topmost layer, is rich in organic matter. A Horizon, or topsoil, is where most biological activities occur. P Horizon is mentioned less frequently, but it may refer to the parent material of soil, underlying the other horizons.