The characteristic pigment of Cyanobacteria is

Options

A. chlorophyll a
B. fucoxanthin
C. phycocyanin
D. chlorophyll d

Answer

To determine the characteristic pigment of Cyanobacteria, we will analyze the options provided and understand the unique features of Cyanobacteria.

### Step-by-Step Solution:

1. **Understanding Cyanobacteria**:
- Cyanobacteria are often referred to as blue-green algae. They are photosynthetic bacteria that can produce their own food through photosynthesis.

2. **Identifying the Pigments**:
- Cyanobacteria contain several pigments that aid in photosynthesis. The main pigments include:
- **Chlorophyll-a**: Commonly found in many photosynthetic organisms, including plants.
- **Chlorophyll-d**: Found in red algae, not characteristic of Cyanobacteria.
- **Phycocyanin**: A blue pigment that is specific to Cyanobacteria and gives them their characteristic blue-green color.
- **Fucoxanthin**: A pigment found in brown algae, not present in Cyanobacteria.

3. **Evaluating the Options**:
- **Chlorophyll-a**: While present in Cyanobacteria, it is not unique to them as it is also found in green plants.
- **Chlorophyll-d**: This is not found in Cyanobacteria; it is specific to red algae.
- **Phycocyanin**: This is a unique pigment that is characteristic of Cyanobacteria and gives them their blue-green color.
- **Fucoxanthin**: This pigment is associated with brown algae and is not found in Cyanobacteria.

4. **Conclusion**:
- The characteristic pigment of Cyanobacteria is **Phycocyanin**. This pigment distinguishes them from other photosynthetic organisms.

### Final Answer:
The characteristic pigment of Cyanobacteria is **Phycocyanin**.