The correct options are
A Nitrogen fixation
B Nitrogen assimilation
C Ammonification
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into various chemical forms, as it circulates among the atmosphere, terrestrial, and marine ecosystems.
The Nitrogen Cycle involves:
i. Nitrogen fixation
ii. Nitrogen assimilation
iii. Ammonification
iv. Nitrification
v. Denitrification