Brown algae vary in colour from olive green to various shades of brown depending upon the amount of the pigment

Options

A. r-phycoerythin
B. ciolaxanthin
C. laminarin
D. fucoxanthin

Answer

**Step-by-Step Solution:**

1. **Understanding Brown Algae**: Brown algae belong to the class Pheophyceae and are characterized by their brown color, which can vary from olive green to various shades of brown.

2. **Identifying the Pigments**: The color variation in brown algae is primarily due to the presence of specific pigments. The main pigments found in brown algae include:
- Chlorophyll A
- Chlorophyll C
- Fucoxanthin (the pigment responsible for the brown color)

3. **Role of Fucoxanthin**: Among the pigments mentioned, Fucoxanthin is the key pigment that gives brown algae their characteristic brown color. The presence and concentration of Fucoxanthin determine the shade of brown.

4. **Other Pigments**: While other pigments like Phycoerythrin (which gives red algae their color) and Violaxanthin are present in algae, they do not contribute to the brown color of brown algae.

5. **Conclusion**: Therefore, the pigment responsible for the brown color in brown algae is Fucoxanthin.

**Final Answer**: The pigment responsible for the brown color in brown algae is Fucoxanthin.

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