Oxygenic photosynthesis occurs in

Options

A. Rhodospirillum
B. Chlorobium
C. Chromatium
D. Oscillatoria

Explanation

To determine where oxygenic photosynthesis occurs, we need to analyze the options provided and understand the concept of oxygenic photosynthesis itself.

### Step-by-Step Solution:

1. **Understanding Oxygenic Photosynthesis**:
- Oxygenic photosynthesis is a process where oxygen is produced as a byproduct of photosynthesis. This occurs when organisms use light energy to convert carbon dioxide and water into glucose and oxygen.

2. **Identifying Organisms**:
- The question provides four options: Rhodospirillum, Chlorobium, Chromatium, and Oscillatoria. We need to identify which of these organisms can perform oxygenic photosynthesis.

3. **Analyzing the Options**:
- **Rhodospirillum**: This is a type of purple non-sulfur bacteria that performs anoxygenic photosynthesis, meaning it does not produce oxygen.
- **Chlorobium**: This is a green sulfur bacterium that also performs anoxygenic photosynthesis and does not produce oxygen.
- **Chromatium**: Similar to Chlorobium, Chromatium is a green sulfur bacterium and does not perform oxygenic photosynthesis.
- **Oscillatoria**: This is a genus of cyanobacteria, which are known to perform oxygenic photosynthesis. They utilize light energy to produce oxygen.

4. **Conclusion**:
- Based on the analysis, the only organism among the options that performs oxygenic photosynthesis is **Oscillatoria**. Therefore, the correct answer is **Option D**.

### Final Answer:
Oxygenic photosynthesis occurs in **Oscillatoria**.

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