Experiment for Emerson enhancement and red drop was conducted on :

Options

A. Chlamydomonas
B. Polysinphonia
C. Chlorella
D. Dictyota

Answer

To solve the question regarding the experiment for Emerson enhancement and red drop, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concepts**:
- The Emerson enhancement effect refers to the increase in photosynthetic efficiency when plants are exposed to light of two different wavelengths, specifically red and far-red light.
- The red drop is the phenomenon where there is a decrease in photosynthetic yield when light wavelengths exceed 680 nanometers, which is in the far-red region of the electromagnetic spectrum.

2. **Identifying the Researchers**:
- The experiment related to the Emerson enhancement effect and red drop was conducted by researchers Emerson and Lewis.

3. **Identifying the Organism Used**:
- The question lists several organisms: Chlamydomonas, Polysiphonia, Chlorella, and Dictiota.
- It is important to know which organism was specifically used in the experiments conducted by Emerson and Lewis.

4. **Recalling the Correct Organism**:
- The correct organism used in the experiments by Emerson and Lewis to demonstrate the red drop and enhancement effect is **Chlorella**.

5. **Final Answer**:
- Therefore, the answer to the question is option number three: **Chlorella**.