`overset(i)to` a nitrifying bacteria, oxidises `overset(ii)to` into nitrites.

Options

A. i-Bacillus vulgaris, ii-free nitrogen
B. i-Bacillus ramosus, ii-nitrates
C. i-Nitrosomonas communis, ii-ammonia
D. i-Pseudomonas aeruginosa, ii-protein

Answer

To solve the question regarding nitrifying bacteria, we need to identify the specific bacteria that oxidizes ammonia into nitrites. Let's break down the solution step by step:

### Step-by-Step Solution:

1. **Understanding Nitrifying Bacteria**:
- Nitrifying bacteria are microorganisms that play a crucial role in the nitrogen cycle. They convert ammonia (NH₃) into nitrites (NO₂⁻) and then into nitrates (NO₃⁻).

2. **Identifying the Process**:
- The process by which ammonia is converted into nitrites is known as nitrification. This process involves two main groups of bacteria:
- **Ammonia-oxidizing bacteria (AOB)**: These bacteria convert ammonia into nitrites.
- **Nitrite-oxidizing bacteria (NOB)**: These bacteria convert nitrites into nitrates.

3. **Analyzing the Options**:
- The options provided are:
- Bacillus vulgaris
- Free nitrogen
- Bacillus ramosus
- Nitrosomonas communis
- Pseudomonas aeruginosa
- Among these, we need to identify which one is a nitrifying bacterium that specifically oxidizes ammonia to nitrites.

4. **Selecting the Correct Bacterium**:
- **Nitrosomonas communis** is a well-known nitrifying bacterium that specifically oxidizes ammonia (NH₃) into nitrites (NO₂⁻).
- The other options, such as Bacillus vulgaris and Bacillus ramosus, are not primarily known for this function; they are more associated with ammonification or other processes.

5. **Final Answer**:
- Therefore, the correct answer to the question is:
- **Nitrosomonas communis** oxidizes ammonia into nitrites.