Question

which of the following processes is shown by arrow 2 in the image below?* nitrification nitrogen fixation denitrification producer uptake

Explanation:

Nitrification is the process by which ammonia is converted into nitrites ($NO_2^-$) and then into nitrates ($NO_3^-$). In the nitrogen cycle diagram, arrow 2 represents the conversion of ammonia (from excretion) into forms that can be used by producers. Nitrogen fixation (by lightning or bacteria) is a different process (arrow related to lightning is shown separately). Denitrification is the conversion of nitrates to nitrogen gas ($N_2$) (arrow 1 in some nitrogen - cycle interpretations related to gas release). Producer uptake is a different process (arrow labeled as such in the diagram).

Answer:

Nitrification