Denitrifying bacteria

release ammonia
make proteins from nitrates
change nitrogen into ammonia
change ammonia and nitrates into nitrogen

Im pretty sure its C

Explanation:

Denitrifying bacteria release nitrogen by breaking down ammonia and nitrates. This process called denitrification. Nitrogen from denitrification is released into the atmosphere. The rate at which nitrogen is removed from the atmosphere by fixation is balanced by the rate at which nitrogen is returned to the atmosphere by denitrification. This balance may be upset by the use of artificial fertilizers. More nitrogen may be fixed than can be returned by denitrification.

oceans

indian ocean

pacific ocean

atlantic ocean

arctic ocean

southern ocean

if you know your abc's you should be able to get your answer or just use google