All chordates at one or the other stage possess

Options

A. Two pairs of pentadactyl limbs
B. Movable jaw
C. Vertebral column
D. Pharyngeal gill slits

Answer

**Step-by-Step Solution:**

1. **Understanding Chordates**: Chordates are a diverse group of animals that share certain key features at some stage of their development. The three primary characteristics that define chordates are the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits.

2. **Analyzing the Options**:
- **Two pairs of pentadactyl limbs**: This feature is not universally present in all chordates. It is characteristic of tetrapods (four-limbed vertebrates), but not all chordates have limbs.
- **Movable jaw**: While many chordates, especially vertebrates, have a movable jaw, it is not a feature present in all chordates, particularly in some primitive forms.
- **Vertebral column**: Not all chordates have a vertebral column. For example, invertebrate chordates like tunicates and lancelets possess a notochord instead of a vertebral column.
- **Pharyngeal gill slits**: This is a feature that is present in all chordates at some stage of their development, making it the correct answer.

3. **Conclusion**: The correct answer to the question is that all chordates at one or another stage possess pharyngeal gill slits, along with the notochord and dorsal hollow nerve cord.

**Final Answer**: All chordates at one or another stage possess pharyngeal gill slits.

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