Which one of the following is not a character of brown algae?

Options

A. Presence of chlorophyll a and b
B. It remains attached to substratum
C. Presence of chlorophyll a and c
D. Presence of fucoxanthin

Answer

To determine which character is not associated with brown algae, we need to analyze the given options based on the known characteristics of brown algae.

### Step-by-Step Solution:

1. **Understanding Brown Algae**:
Brown algae belong to the class Phaeophyceae and are primarily found in marine environments. They are characterized by their brown color, which is due to the presence of the pigment fucoxanthin.

2. **Identifying Chlorophyll Types**:
Brown algae contain chlorophyll A and chlorophyll C. They do not contain chlorophyll B, which is typically found in green algae (Chlorophyta).

3. **Attachment to Substratum**:
Brown algae are attached to the substratum using a structure called a holdfast. This is a common characteristic of many algae, including brown algae.

4. **Presence of Fucoxanthin**:
Fucoxanthin is a specific pigment found in brown algae that contributes to their color. This is indeed a characteristic of brown algae.

5. **Stored Food**:
The main storage products in brown algae are mannitol and laminarin, which are different from the starch stored in green algae.

6. **Conclusion**:
Among the options provided, the presence of chlorophyll A and B is not a characteristic of brown algae. Instead, they contain chlorophyll A and C. Therefore, the option stating the presence of chlorophyll A and B is the correct answer to the question.

### Final Answer:
The character that is not associated with brown algae is the presence of **Chlorophyll A and B**.