An unarmoured dinoflagellate is

Options

A. Ceratium
B. Noctiluca
C. Gonyaulax
D. Both B and C.

Answer

To determine which unarmoured dinoflagellate is being referred to in the question, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Classification**:
- Dinoflagellates are a type of unicellular eukaryotes that belong to the kingdom Protista. Recognizing their classification helps in identifying their characteristics.

2. **Identify Armoured vs. Unarmoured Dinoflagellates**:
- Some dinoflagellates have a protective covering known as amphiesma, which is made of cellulose. This covering can be classified into two layers: an outer and an inner layer.

3. **Analyze the Options Given**:
- The question likely provides multiple options for dinoflagellates. We need to evaluate each option based on whether they are armored or unarmoured.

4. **Evaluate Each Option**:
- **Serratia**: This dinoflagellate has amphiesma, meaning it is armored.
- **Noctiluca**: This dinoflagellate does not have amphiesma, indicating that it is unarmoured.
- **Gonyaulax**: This is a red dinoflagellate that has a resting cyst and is also armored due to the presence of amphiesma.

5. **Select the Correct Answer**:
- Based on the evaluation, the only unarmoured dinoflagellate among the options is **Noctiluca**. Therefore, the correct answer to the question is Noctiluca.

### Final Answer:
The unarmoured dinoflagellate is **Noctiluca**.

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