An incorrect character of brown algae is `:`

Options

A. presence of chlorophyll a and d
B. presence of mannitol
C. presence of phycocolloids
D. presence of fucoxanthin.

Answer

To determine the incorrect character of brown algae, we need to analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understand the Classification of Brown Algae**:
- Brown algae belong to the class Phaeophyceae. They are characterized by specific pigments and storage compounds.

2. **Analyze the Options**:
- **Option 1: Presence of chlorophyll A and D**:
- Brown algae contain chlorophyll A and chlorophyll C, but they do not contain chlorophyll D. Therefore, this option is incorrect.
- **Option 2: Presence of mannitol**:
- Mannitol is indeed present in brown algae and serves various functions, including carbon storage and acting as an osmoprotectant. This option is correct.
- **Option 3: Presence of phycocolloids**:
- Brown algae contain phycocolloids, which are important for their structure and function. This option is also correct.
- **Option 4: Presence of phycoxanthine**:
- Phycoxanthine is a pigment found in brown algae that contributes to their brown color. This option is correct as well.

3. **Identify the Incorrect Character**:
- The only incorrect character among the options is **Option 1: Presence of chlorophyll A and D**. Instead of chlorophyll D, brown algae have chlorophyll C.

### Final Answer:
The incorrect character of brown algae is the **presence of chlorophyll A and D**.

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