T. W. Engelmann performed his experiments on which of the following ?

Options

A. Cladophora - a green algae .
B. Cladophora - an aerobic .
C. Chlorobium - a green algae .
D. Chlorobium - an aerobic bacteria.

Answer

To solve the question regarding T.W. Engelmann's experiments, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Subject of the Experiment**:
- T.W. Engelmann is known for his work in photosynthesis. The question asks what he performed his experiments on.

2. **Recall the Purpose of Engelmann's Experiment**:
- Engelmann aimed to determine the action spectrum of photosynthesis. This involves understanding which wavelengths of light are most effective for photosynthesis.

3. **Understand the Experimental Setup**:
- Engelmann used a green algae called Cladophora in his experiments. He illuminated this algae and placed it in a suspension of aerobic bacteria.

4. **Analyze the Results**:
- After illuminating the algae, Engelmann observed that the aerobic bacteria accumulated mainly in the regions of blue and red light. This indicated that these wavelengths were most effective for photosynthesis.

5. **Conclude with the Correct Answer**:
- Based on Engelmann's experiment, the correct answer to the question is that he performed his experiments on **Cladophora**, a type of green algae.

### Final Answer:
- T.W. Engelmann performed his experiments on **Cladophora** (green algae).

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