Fucoxanthin occurs in

Options

A. Cyanophyceae
B. Rhodophyceae
C. Chlorophyceae
D. Phaeophyceae.

Answer

To answer the question "Fucoxanthin occurs in," we need to analyze the options provided and identify where fucoxanthin is found among the different classes of algae.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the occurrence of fucoxanthin, which is an accessory pigment. We need to identify in which group of algae this pigment is present.

2. **Review the Options**: The options given are:
- A) Cyanophyce (Blue-green algae)
- B) Rhodophyce (Red algae)
- C) Chlorophyce (Green algae)
- D) Pheophyce (Brown algae)

3. **Analyze Cyanophyce**:
- Cyanophyce, or blue-green algae, are prokaryotic and primarily contain chlorophyll A along with other pigments like phycocyanin and phycoerythrin.
- **Conclusion**: Fucoxanthin is not present in Cyanophyce.

4. **Analyze Rhodophyce**:
- Rhodophyce, or red algae, contain pigments such as chlorophyll A, chlorophyll D, beta-carotene, phycoerythrin, and phycocyanin.
- **Conclusion**: Fucoxanthin is not present in Rhodophyce.

5. **Analyze Chlorophyce**:
- Chlorophyce, or green algae, contain chlorophyll A, chlorophyll B, beta-carotene, and xanthophyll.
- **Conclusion**: Fucoxanthin is not present in Chlorophyce.

6. **Analyze Pheophyce**:
- Pheophyce, or brown algae, contain chlorophyll A, fucoxanthin (which is the pigment we are looking for), and beta-carotene.
- **Conclusion**: Fucoxanthin is present in Pheophyce.

7. **Final Answer**: Based on the analysis, fucoxanthin occurs in **D) Pheophyce (Brown algae)**.