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 the given options one by one:

1. **Presence of chlorophyll A and D**:
- Brown algae primarily contain chlorophyll A and C, not D. Therefore, this statement is incorrect.

2. **Presence of mannitol**:
- Mannitol is indeed a storage carbohydrate found in brown algae. This statement is correct.

3. **Presence of phycocollides**:
- Phycocollides, such as algin, are substances that can hold water and are produced by brown algae. This statement is correct.

4. **Presence of fucoxanthin**:
- Fucoxanthin is a pigment that gives brown algae their characteristic color and is present in them. This statement is also correct.

Based on the analysis, the incorrect character of brown algae is the **presence of chlorophyll A and D**.

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

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