One of the free-living anaerobic nitrogen-fixer is
Azotobacter
Beijernickia
Rhodospirillum
Rhizobium
Select the matched ones:
(1)Nitrosomonas - Nitrite to nitrate
(2)Thiobacillus - Denitrification
(3)Nostoc– Free - living nitrogen-fixer
(4)Azotobacter - Anaerobic nitrogen-fixer