Select the correct match
`{:("(A) Nirosomonas - Nitrite to nitrate"),("(B) Thiobacillus - Denitrification"),("(C) Nostoc - Free-living nitrogen-fixer"),("(D) Azotobacter - Anaerobic nitrogen-fixer"):}`

Options

A. a) A and B
B. b) C and D
C. c) B and C
D. d) B and D

Answer

To solve the question, we need to analyze each of the given matches and determine which ones are correct.

1. **Match (A): Nirosomonas - Nitrite to nitrate**
- Nirosomonas is actually a genus of bacteria that converts ammonia (NH3) into nitrite (NO2-), not nitrite to nitrate. Therefore, this match is incorrect.

2. **Match (B): Thiobacillus - Denitrification**
- Thiobacillus is a genus of bacteria that is involved in the process of sulfur oxidation and does not primarily participate in denitrification. Denitrification is typically carried out by other bacteria. Thus, this match is also incorrect.

3. **Match (C): Nostoc - Free-living nitrogen-fixer**
- Nostoc is a genus of cyanobacteria that can fix atmospheric nitrogen and is indeed a free-living nitrogen-fixer. This match is correct.

4. **Match (D): Azotobacter - Anaerobic nitrogen-fixer**
- Azotobacter is a genus of bacteria known for fixing nitrogen, but it is an aerobic nitrogen-fixer, not anaerobic. Therefore, this match is incorrect.

Based on the analysis:
- The correct matches are **C (Nostoc - Free-living nitrogen-fixer)**.
- The incorrect matches are A, B, and D.

Thus, the correct answer is option **C** which includes the correct matches of B and C.