Question

which stage of the nitrogen cycle does the arrow in the image represent? choose 1 answer: a nitrogen fixation, in which nitrogen gas is converted into ammonia. b denitrification, in which nitrate is converted to nitrogen gas and returned to the atmosphere. c nitrification, in which ammonia is oxidized to nitrite and eventually nitrate. d ammonification, in which organic nitrogen is converted into ammonia or ammonium.

Explanation:

Nitrogen fixation is the process where atmospheric nitrogen gas ($N_2$) is converted into ammonia ($NH_3$) by nitrogen - fixing bacteria. Denitrification is the reverse process of returning nitrogen to the atmosphere from nitrate. Nitrification involves the oxidation of ammonia to nitrite and nitrate. Ammonification is the conversion of organic nitrogen to ammonia or ammonium. Without seeing the image, but based on the definitions, if the arrow shows nitrogen gas being converted to ammonia, it is nitrogen fixation.

Answer:

A. Nitrogen fixation, in which nitrogen gas is converted into ammonia.