. The nitrifying bacteria are
- These are the bacteria that change ammonia/ammonium to nitrite or change nitrite into nitrate.
- These bacteria are an important part of the nitrogen cycle, as they play a very important role in nitrogen fixation.
- These bacteria are chemosynthetic bacteria, they use inorganic energy to synthesize organic compounds (food).
- Examples: Nitrosomonas, Nitrococcus, Nitrobacter.
So the nitrifying bacteria are Chemosynthetic, option D is correct.