Which of the following is a cephalochordate ?

Options

A. Ascidia
B. Salpa
C. Branchiostoma
D. Doliolum

Answer

To determine which of the given options is a cephalochordate, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Cephalochordates**:
- Cephalochordates are a group of marine animals that possess a notochord, which is a flexible rod-like structure that provides support. This notochord extends from the head to the tail and persists throughout the organism's life.

2. **Analyze the Given Options**:
- The options provided are:
- Aschidia
- Salpa
- Branchiostoma
- Doliola

3. **Identify the Classification of Each Option**:
- **Aschidia**: This organism belongs to the Urochordata, which are characterized by having a notochord only during their larval stage.
- **Salpa**: This is also classified under Urochordata, similar to Aschidia.
- **Doliola**: Like the previous two, Doliola is also a member of the Urochordata.
- **Branchiostoma**: This organism is known as Amphioxus and is classified under Cephalochordata.

4. **Determine the Correct Answer**:
- Since Branchiostoma is the only organism listed that belongs to the Cephalochordata group, it is the correct answer to the question.

### Final Answer:
- **Branchiostoma** is the cephalochordate among the options provided.

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