Distinctive feature of chordates is

Options

A. dorsal heart
B. solid nerve cord
C. absence of tail
D. notochord

Answer

To answer the question about the distinctive features of chordates, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Identify Chordates**: Chordates are a group of animals that share certain key characteristics during at least one stage of their development.

2. **List Distinctive Features**: The main distinctive features of chordates include:
- **Notochord**: A flexible rod-like structure that provides support.
- **Dorsal Hollow Nerve Cord**: A nerve cord located along the back (dorsal side) of the organism, which is hollow.
- **Pharyngeal Slits**: Openings in the pharynx that may develop into gills or other structures.
- **Post-anal Tail**: An extension of the body past the anal opening.

3. **Evaluate Options**: If the question provides multiple-choice options, we need to evaluate which of these features is the most distinctive or unique to chordates.

4. **Select the Correct Answer**: Based on the distinctive features listed, the notochord is a defining characteristic of chordates that sets them apart from other animal groups.

5. **Conclusion**: Therefore, the distinctive feature of chordates is the presence of a notochord.

### Final Answer:
The distinctive feature of chordates is the **notochord**.

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