Study the given biogeochemical cycle and identify the steps (i) and (ii)

Biogeochemical cycle - The movement of nutrients and different components among biotic and abiotic factors is called the biogeochemical cycle. The nitrogen cycle has given steps -
(I) Nitrogen fixation
(ii) Nitrification
(iii) Assimilation
(iv) Ammonification
(v) Denitrification

The above-given cycle is a nitrogen cycle, in which (i) is ammonification and (ii) is denitrification.

The step in which decomposers or bacteria break down organic waste like dry leaves and dead organisms that contain nitrogen-containing substances into nitrogen is referred to as ammonification.

Bacteria breakdown the nitrates into nitrites and then into nitrogen. The bacteria in the identification are not exposed to oxygen. 

Hence, option A is the correct answer.