Chordates are characterised by

Options

A. ventral nerve cord
B. dorsal heart
C. post - anal tail
D. pre-anal tail

Answer

### Step-by-Step Solution:

1. **Understanding Chordates**: Chordates are a diverse group of animals that share certain key characteristics during some stage of their development.

2. **Identifying Key Features**: The four main characteristics that define chordates are:
- Presence of a notochord
- Presence of a dorsal nerve cord
- Presence of pharyngeal slits
- Presence of a post-anal tail

3. **Analyzing the Options**: The question provides four options:
- A) Ventral nerve cord
- B) Dorsal heart
- C) Post-anal tail
- D) Pre-anal tail

4. **Evaluating Each Option**:
- **Option A (Ventral nerve cord)**: This is incorrect because chordates have a dorsal nerve cord, not a ventral one.
- **Option B (Dorsal heart)**: This is also incorrect as it does not represent a defining characteristic of chordates.
- **Option C (Post-anal tail)**: This is correct. Chordates are characterized by the presence of a post-anal tail.
- **Option D (Pre-anal tail)**: This is incorrect as chordates do not have a pre-anal tail.

5. **Conclusion**: Based on the analysis, the correct characteristic that defines chordates from the given options is **C) Post-anal tail**.