Answer: c. It determines the pore space within soil horizons.
Soil structure can be defined as the arrangement of the components of the soil. It can be determined by how soil granules of soil aggregate together. The aggregation of soil particles affects the porosity of soil. Porosity can be defined as the amount of pores or spaces that are present in the soil. Pores allows the movement of water and air inside the soil. Pores are necessary to allow the growth of microbes, insects and plants. Hence, pores favors biological activity in the soil.
Soil horizons refers to the layers of soils lying parallel to the earth surface. The layer of soil with more number of pores will favor higher biological activity than the layer with lower number of pores.
Therefore, pore spaces within the soil horizons are structures that affect the characteristics of soil.
