Sea weeds belong to :-

Options

A. Red algae
B. Brown algae
C. Green algae
D. Blue green algae

Answer

To determine the classification of seaweeds, we need to analyze the options provided:

1. **Identify the options**: The question provides four options: red algae, brown algae, green algae, and blue-green algae.

2. **Evaluate red algae**:
- Red algae contain the pigment phycoerythrin, which gives them a red color.
- Seaweeds are not primarily classified under red algae.
- Therefore, this option is incorrect.

3. **Evaluate brown algae**:
- Brown algae are multicellular and are known to include various types of seaweeds.
- They thrive in colder waters and are characterized by the presence of the pigment fucoxanthin, which gives them their brown color.
- This option is correct as seaweeds belong to this category.

4. **Evaluate green algae**:
- Green algae contain chlorophyll A and B, which are responsible for their green color.
- While they are important in aquatic ecosystems, they do not include seaweeds.
- Thus, this option is also incorrect.

5. **Evaluate blue-green algae**:
- Blue-green algae, also known as cyanobacteria, are not true algae but rather photosynthetic bacteria.
- They do not fall under the classification of seaweeds.
- Therefore, this option is incorrect as well.

6. **Conclusion**: Based on the evaluations, the correct classification for seaweeds is **brown algae**.

### Final Answer:
Seaweeds belong to **brown algae**.