Small pox' (Variola) disease is caused by

Options

A. virus
B. Bacterium
C. Helminth
D. Protozoan

Answer

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about the cause of "smallpox" (Variola).

2. **Recall the Nature of Smallpox**: Smallpox is known to be a contagious disease that has been eradicated since 1980.

3. **Determine the Causative Agent**: The options given are:
- Virus
- Bacterium
- Helminth
- Protozoan

4. **Research Historical Context**: Smallpox was eradicated due to a global vaccination program, which was significantly influenced by the work of Edward Jenner, who developed the smallpox vaccine.

5. **Identify the Correct Option**: Smallpox is caused by a virus known as the variola virus. Therefore, the correct answer is the first option: **Virus**.

6. **Eliminate Incorrect Options**:
- Bacterium: Not applicable as smallpox is not caused by bacteria.
- Helminth: Not applicable as smallpox is not caused by helminths (worms).
- Protozoan: Not applicable as smallpox is not caused by protozoans.

7. **Final Conclusion**: The causative agent of smallpox (Variola) is a virus, specifically the variola virus.

**Final Answer**: Smallpox (Variola) disease is caused by a **virus**.

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