Action spectrum of photosynthesis was discovered by

Options

A. Van Niel
B. Engelman
C. Blackman
D. None of these

Answer

To answer the question "Action spectrum of photosynthesis was discovered by," we need to analyze the options provided and identify the correct scientist associated with the discovery of the action spectrum in photosynthesis.

### Step-by-Step Solution:

1. **Understanding Action Spectrum**: The action spectrum of photosynthesis refers to the range of wavelengths of light that are effective in driving the process of photosynthesis. It shows which wavelengths are most effective for photosynthesis.

2. **Identifying Key Scientists**: The question provides four options:
- A. Van Neel
- B. Engelman
- C. Blackman
- D. None of these

3. **Evaluating Each Option**:
- **A. Van Neel**: He is known for his work on purple sulfur bacteria and the concept of photosynthesis as a light-dependent redox reaction. However, he did not discover the action spectrum.
- **B. Engelman**: He is the scientist who is credited with discovering the action spectrum of photosynthesis. Engelman used a prism to separate light into its components and observed the effects on photosynthesis in algae.
- **C. Blackman**: He is known for Blackman's law of limiting factors, which describes how different factors can limit the rate of photosynthesis. He did not discover the action spectrum.
- **D. None of these**: This option would imply that none of the listed scientists discovered the action spectrum, which is incorrect.

4. **Conclusion**: Based on the evaluation, the correct answer is **B. Engelman**, as he was the scientist who discovered the action spectrum of photosynthesis.

### Final Answer:
The action spectrum of photosynthesis was discovered by **B. Engelman**.