Process of intermixing of soil horizons by external factors is called:

Correct option is D

Pedoturbation refers to the mechanical mixing of soil horizons caused by external factors such as plant roots, animals, or physical disturbances (like wind or water). This process can affect the structure and composition of the soil layers. It helps in the mixing of the organic and mineral horizons, which can influence nutrient availability and soil fertility. This is important in soil science for understanding how soil profiles change over time.