Which of the following groups of algae belongs to class Rhodophyceae ?

Options

A. Ectocarpus , Dictyota, Fucus, and sargassum
B. Ectocarpus , Dictyota , porphyra , and Gracilaria
C. Chlamydomonas Volvox , Ulothrix , and Fucus
D. Sargassum , Dictyota , Gracilaria , and Gelidium

Answer

To determine which group of algae belongs to the class Rhodophyceae, we will analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understand the Classification**:
- Algae are classified into different classes based on their characteristics. Rhodophyceae is the class that includes red algae.

2. **Identify Key Characteristics of Rhodophyceae**:
- Members of the class Rhodophyceae are typically red in color due to the presence of phycoerythrin pigment. They are mostly found in marine environments.

3. **List the Given Options**:
- The options provided in the question include various types of algae. We need to identify which of these belong to Rhodophyceae.

4. **Analyze Each Option**:
- **Gracilaria**: This is a type of red algae and belongs to Rhodophyceae.
- **Gelidium**: This is also a red algae and belongs to Rhodophyceae.
- **Porphyra**: This is another example of red algae and belongs to Rhodophyceae.
- **Polysiphonia**: This is also classified under Rhodophyceae.

5. **Identify Non-Rhodophyceae Options**:
- **Sargassum**: This is a brown algae and belongs to the class Phaeophyceae.
- **Fucus**: This is also a brown algae and belongs to Phaeophyceae.
- **Ectocarpus**: This is a brown algae and belongs to Phaeophyceae.
- **Dictyota**: This is a brown algae and belongs to Phaeophyceae.
- **Laminaria**: This is also a brown algae and belongs to Phaeophyceae.

6. **Conclusion**:
- The groups of algae that belong to the class Rhodophyceae are Gracilaria, Gelidium, Porphyra, and Polysiphonia.

### Final Answer:
The groups of algae that belong to the class Rhodophyceae are Gracilaria, Gelidium, Porphyra, and Polysiphonia.