Final answer:
The false statement in the choices provided regarding the nitrogen cycle is that nitrification converts nitrites to ammonium, which is incorrect as nitrification involves the oxidation of ammonium to nitrites and then to nitrates.
Step-by-step explanation:
The nitrogen cycle is essential for converting atmospheric nitrogen into a form that is usable by living organisms. The false statement among the choices provided is: d. Nitrification is the process by which nitrites (NO2-) are converted to ammonium ion (NH4+). In reality, nitrification is a two-step process where ammonia (NH3) or ammonium ion (NH4+) is first oxidized to nitrites (NO2-) by bacteria, such as those of the genus Nitrosomonas, and then the nitrites are further oxidized to nitrates (NO3-) by bacteria, such as those of the genus Nitrobacter.