Who, after conducting experiments on purple and green sulphur bacteria, inferred that `O_(2)` evolved during photosynthesis comes from `H_(2)O` not from `CO_(2)`?

Options

A. Sachs
B. Engelmann
C. van Niel
D. Blackmann

Explanation

**Step-by-Step Solution:**

1. **Identify the Scientist**: The question asks for the scientist who conducted experiments on purple and green sulfur bacteria and concluded that the oxygen produced during photosynthesis comes from water (H₂O) and not from carbon dioxide (CO₂).

2. **Recall Relevant Experiments**: The scientist who made this inference is Van Niel. He conducted experiments specifically using purple and green sulfur bacteria to study the process of photosynthesis.

3. **Understand the Conclusion**: Van Niel's conclusion was significant because it shifted the understanding of the source of oxygen in photosynthesis. He demonstrated that the oxygen released during photosynthesis originates from water molecules rather than from carbon dioxide.

4. **Differentiate Other Scientists**: It is important to distinguish Van Niel's work from that of other scientists mentioned:
- Julius Sack focused on the formation of glucose and its storage as starch.
- Engelman discovered the light spectrum used in photosynthesis and identified the effectiveness of blue and red light.
- Blackman formulated the law of limiting factors in photosynthesis, which describes how various factors like light, CO₂, temperature, and water affect the rate of photosynthesis.

5. **Final Answer**: Therefore, the answer to the question is Van Niel.

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