Red tide' are produced by -

Options

A. Red Algae
B. Dinoflagellates
C. Diatoms
D. Brown algae

Answer

**Step-by-Step Solution:**

1. **Understanding Red Tides**: Red tides are a phenomenon that occurs in marine environments, characterized by the discoloration of seawater due to the proliferation of certain microorganisms.

2. **Analyzing the Options**: The question provides multiple options for the organisms that produce red tides. We need to evaluate each option to determine which one is correct.

3. **Evaluating Red Algae**: The first option is red algae. It is important to note that red tides are not caused by red algae. Therefore, this option is incorrect.

4. **Evaluating Dinoflagellates**: The second option is dinoflagellates. These are photosynthetic protists that belong to the kingdom Protista. Dinoflagellates contain various pigments, which can be red, orange, yellow, or brown. The red-colored dinoflagellates, specifically a genus called Gonyaulax, are known to cause red tides by blooming in large numbers.

5. **Evaluating Diatoms**: The third option is diatoms. While diatoms are also photosynthetic organisms and contribute to the ocean's productivity, they do not cause red tides. Thus, this option is also incorrect.

6. **Conclusion**: Based on the evaluation of all options, the correct answer to the question "Red tide' are produced by" is **dinoflagellates** (option 2).

**Final Answer**: Dinoflagellates

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