What is the source of inorganic nitrogen?

The correct choice identifies inorganic nitrogen as being sourced from fertilizers and atmospheric sources, which is a key aspect of understanding nitrogen dynamics in agricultural and environmental contexts.

Inorganic nitrogen is primarily found in the form of nitrates and ammonium, which can be provided from synthetic fertilizers used in agriculture. These fertilizers are a direct source of nutrients essential for plant growth and can significantly enhance crop productivity when applied appropriately. Additionally, atmospheric nitrogen is fixed by various processes, including those carried out by certain bacteria and through industrial processes, which convert atmospheric nitrogen (N2) into forms that can be utilized by plants.

Other options that suggest narrow sources, such as animal waste, composting, or decomposing organic matter, primarily relate to organic forms of nitrogen rather than inorganic. While these sources can contribute to the nitrogen cycle, they do not encompass the broader range of inorganic nitrogen available from fertilizers and atmospheric contributions, which makes them less comprehensive in addressing the question regarding sources of inorganic nitrogen.