Dog distemper is a disease carried by a

Options

A. bacterium
B. viroid
C. prion
D. virus

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the causative agent of dog distemper disease. We need to identify whether it is caused by a bacterium, viroid, prion, or virus.

2. **Identifying the Disease**: Dog distemper is a well-known disease that affects dogs. It is important to know the specific characteristics of this disease to determine its cause.

3. **Researching the Causative Agent**: Dog distemper is caused by a specific virus known as Canine Distemper Virus (CDV). This information is crucial as it directly points to the correct answer.

4. **Analyzing the Options**:
- Option 1: Bacterium - This is incorrect as dog distemper is not caused by bacteria.
- Option 2: Viroid - This is also incorrect as viroids are known to cause diseases in plants, not in animals like dogs.
- Option 3: Prion - Prions are infectious agents composed of protein and are associated with certain neurodegenerative diseases, but not with dog distemper.
- Option 4: Virus - This is the correct option since dog distemper is indeed caused by a virus.

5. **Conclusion**: Based on the information gathered, the correct answer to the question is option 4: virus.

**Final Answer**: Dog distemper is a disease carried by a virus.

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