The process of conversion of $2 NO_{3}^{-} \rightarrow 2 NO_{2}^{-} \rightarrow 2 NO \rightarrow N_{2}O \rightarrow N_{2}$ is called and is carried out by:

• A
  Nitrification,Nitrosomonas
• B
  Denitrification,Pseudomonas
• C
  Nitrate assimilation,Nitrogenase
• D
  Ammonification,Bacillus