Which of the following is a bacterium involved in denitrification?

Denitrification is the last and final step if nitrogen cycle, wherein, the nitrates (NO3 – )      present in the soil are converted into molecular dinitrogen, in order to maintain the equilibrium    of nitrogen in the atmosphere. The bacteria responsible for this reaction are called denitrifying bacteria. This process is brought about by denitrifying bacteria like Thiobacillus denitrificans. Pseudomonas denitrificans and Micrococcus denitrificans.