Match Column-I with Column-II.
| Column-I | Column-II |
|---|---|
| (a) Nitrococcus | (i) Denitrification |
| (b) Rhizobium | (ii) Conversion of ammonia to nitrite |
| (c) Thiobacillus | (iii) Conversion of nitrite to nitrate |
| (d) Nitrobacter | (iv) Conversion of atmospheric nitrogen to ammonia |
Choose the correct answer from the options given below: