Food is stored as floeidean starch in Rhodophyceae. Mannitol is the reserve food material of which group of algae ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the reserve food material known as mannitol and which group of algae it is associated with.

2. **Identifying the Key Terms**: The key terms in the question are "mannitol" and "group of algae." We need to find out which group of algae stores food as mannitol.

3. **Recalling Information about Algae**:
- We know that Rhodophyceae (red algae) store food as Floridian starch.
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