all vertebrates posses

Options

A. renal portal system
B. dorsal, hollow, central nervous system
C. four chambered ventral heart
D. pharyngeal gill slits

Explanation

To answer the question "What do all vertebrates possess?", we will evaluate each of the options provided and determine which one is universally present in all vertebrates.

### Step-by-Step Solution:

1. **Evaluate the Renal Portal System**:
- The renal portal system is a feature that is involved in the blood supply to the kidneys. However, it is absent in certain vertebrates such as hagfishes and mammals. Therefore, this system is not present in all vertebrates.
- **Conclusion**: This option can be eliminated.

2. **Evaluate the Dorsal Hollow Central Nervous System**:
- The dorsal hollow central nervous system is a defining characteristic of vertebrates. It consists of a spinal cord and a brain, and it is present in all vertebrate species. This feature distinguishes vertebrates from invertebrates.
- **Conclusion**: This option is a strong candidate for the answer.

3. **Evaluate the Four-Chambered Ventral Heart**:
- The heart structure varies among vertebrates. Fish typically have a two-chambered heart, amphibians have a three-chambered heart, and mammals possess a four-chambered heart. Since not all vertebrates have a four-chambered heart, this option can also be eliminated.
- **Conclusion**: This option is not universally applicable to all vertebrates.

4. **Evaluate the Pharyngeal Gill Slits**:
- Pharyngeal gill slits are present in the embryonic stages of all vertebrates, but they may not be retained in adult forms (e.g., they are absent in mammals). Therefore, this characteristic is also not present in all vertebrates in their adult form.
- **Conclusion**: This option can be eliminated as well.

### Final Answer:
The only feature that is present in all vertebrates is the **dorsal hollow central nervous system**.

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