Which one of the following pairs is not correcly matched?

Options

A. Choetopleura - Chiton
B. Ascaris - Round worm
C. Wuchereria - Filaria worm
D. Enterobius - Hook worm

Answer

To determine which pair is not correctly matched, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Evaluate the First Option: Keto Plura and Chitin**
- Keto Plura is commonly known as "Caytan."
- Chitin is a structural component found in the exoskeletons of arthropods and in the cell walls of fungi, but it is not specifically associated with Keto Plura.
- **Conclusion**: This pair is incorrectly matched.

2. **Evaluate the Second Option: Ascaris and Roundworm**
- Ascaris is indeed a type of roundworm.
- The term "roundworm" is commonly used to refer to nematodes, which include Ascaris.
- **Conclusion**: This pair is correctly matched.

3. **Evaluate the Third Option: Machaeria and Filaria**
- Machaeria is not a commonly recognized name associated with filarial worms.
- Filaria typically refers to a group of parasitic worms, but Machaeria does not fit this classification.
- **Conclusion**: This pair is incorrectly matched.

4. **Evaluate the Fourth Option: Enterobius and Hookworm**
- Enterobius is commonly known as the pinworm.
- Hookworms are a different group of parasitic worms and are not associated with Enterobius.
- **Conclusion**: This pair is incorrectly matched.

### Final Answer:
The pairs that are not correctly matched are:
- **Keto Plura and Chitin**
- **Machaeria and Filaria**
- **Enterobius and Hookworm**

However, since the question asks for a single incorrect match, the most straightforward answer is **Enterobius and Hookworm**, as Enterobius is specifically known as the pinworm.