Phycobilins occur in

Options

A. Green algae
B. Blue-green Algae
C. Red algae
D. Both B and C.

Answer

### Step-by-Step Solution:

1. **Understanding Phycobilins**:
- Phycobilins are light-capturing pigments that belong to the class of biliproteins. They play a crucial role in photosynthesis by acting as accessory pigments.

2. **Identifying the Types of Algae**:
- Phycobilins are primarily found in certain types of algae. The main groups of algae that contain phycobilins are red algae (Rhodophyta) and blue-green algae (Cyanobacteria).

3. **Pigments in Red Algae**:
- Red algae contain specific types of phycobilins, namely phycoerythrin (which gives them their red color) and phycocyanin.

4. **Pigments in Blue-Green Algae**:
- Blue-green algae, also known as Cyanobacteria, also contain phycobilins, specifically phycoerythrin and phycocyanin.

5. **Conclusion**:
- Since phycobilins are present in both red algae and blue-green algae, the correct answer to the question "Phycobilins occur in" is option D, which states "both B and C" (referring to red algae and blue-green algae).

### Final Answer:
Phycobilins occur in both red algae and blue-green algae (option D).

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