The purple sulphur bacteria use hydrogen sulphide and release sulphur but not oxygen. Which of the following agrees with above observation

Options

A. The `H_(2)` that reduces `CO_(2)` comes from `H_(2)S` that liberates sulphur
B. Photosynthesis does not require chlorophyll
C. Photosynthesis consist of a light and a dark reaction
D. The `H_(2)` which reduces `CO_(2)` in photosynthesis comes from water that releases `O_2`

Explanation

To solve the question regarding the purple sulphur bacteria and their metabolic process, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Purple Sulphur Bacteria**:
- Purple sulphur bacteria are a type of anaerobic bacteria that utilize hydrogen sulphide (H2S) in their metabolic processes. They are known for their characteristic purple color due to the presence of pigments like chlorophyll and carotenoids.

**Hint**: Recall that purple sulphur bacteria are anaerobic and have specific pigments that give them their color.

2. **Metabolic Process**:
- These bacteria use H2S as an electron donor in their photosynthetic process. Instead of producing oxygen like most plants, they release elemental sulphur as a byproduct.

**Hint**: Focus on the fact that these bacteria do not produce oxygen, which differentiates them from typical photosynthetic organisms.

3. **Photosynthesis Mechanism**:
- In the case of purple sulphur bacteria, the hydrogen from H2S is used to reduce carbon dioxide (CO2) to form carbohydrates. This process does not involve water (H2O) as the electron donor, which is typical in oxygenic photosynthesis.

**Hint**: Remember that the reduction of CO2 in these bacteria comes from H2S, not water.

4. **Conclusion**:
- The correct statement that aligns with the observation of purple sulphur bacteria is that the hydrogen that reduces carbon dioxide comes from H2S, which separates sulphur. This process is distinct from the oxygenic photosynthesis where water is the source of hydrogen and oxygen is released.

**Hint**: Identify the key difference in the source of hydrogen and the byproducts of the process when comparing to typical photosynthesis.

### Final Answer:
The correct option that agrees with the observation is: **Hydrogen reduces carbon dioxide from H2S and that separates sulphur.**