Red tide is caused by an organism which closely by a organism which structures ?

Options

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Answer

### Step-by-Step Solution:

1. **Understanding Red Tide**: Red tide is a phenomenon where water appears red due to the rapid growth of certain types of algae, specifically dinoflagellates. This algal bloom can lead to harmful effects on marine life and can produce toxins that affect human health.

2. **Identifying the Organism**: The organism primarily responsible for red tide is a type of dinoflagellate. One well-known genus is Gonyaulax, which is often associated with these blooms. These organisms can produce toxins, such as saxitoxin, which can cause paralysis in humans.

3. **Evaluating the Options**:
- **Option 1 (Gonyaulax)**: This is a genus of dinoflagellates that causes red tide. They grow in long chains and are known to produce harmful toxins.
- **Option 2 (Euglena)**: This is a single-celled eukaryotic organism, but it is not associated with red tide.
- **Option 3 (Amoeba)**: This unicellular organism can change shape but has no relation to red tide.
- **Option 4 (Paramecium)**: This organism feeds on microorganisms and moves using cilia, but it is also not related to red tide.

4. **Conclusion**: Based on the evaluation, the correct answer is **Option 1 (Gonyaulax)**, as it is the organism that causes red tide.