To Find :
Which element accumulates in the environment due to the use of fertilizers.
Solution :
Most of the fertilizers used in daily practice are nitrogen fertilizers .
When soil became waterlogged, soil organisms take the oxygen they need from nitrates, leaving the nitrogen in a gaseous form which escapes into the air.
Also, nitrogen is very stable and did not participate in most of the reactions.
So, nitrogen is accumulates in the environment .
Therefore, option C. is correct.