Armoured algae are :-

Options

A. Dinoflagellates
B. Euglenoids
C. Red algae
D. Cyanobacteria

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about "armoured algae," which refers to a specific group of algae characterized by their protective structures.

2. **Analyzing the Options**:
- **Option A: Dinoflagellates**: These are unicellular protists that possess a complex cell wall. They have an arrangement of cellulose plates that form protective structures known as theca, which is why they are referred to as "armoured algae."
- **Option B: Euglenoids**: These are also unicellular eukaryotes but lack a true cell wall. Instead, they have a semi-rigid pellicle. Since they do not have armored plates, this option is incorrect.
- **Option C: Red Algae**: Red algae have a cell wall that contains calcium carbonate, but they do not possess armored plates. Therefore, this option is also incorrect.
- **Option D: Cyanobacteria**: Known as blue-green algae, these organisms have a cell wall made of peptidoglycan and lack cellulose. They do not have armored plates, making this option incorrect as well.

3. **Conclusion**: Based on the analysis, the only group that fits the description of "armoured algae" is **dinoflagellates**.

4. **Final Answer**: The correct answer is **A: Dinoflagellates**.

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