The first virus to be purified was the

Options

A. flu virus
B. Tobacco mosaic virus
C. smallpox virus
D. polio virus

Answer

**Step-by-Step Solution:**

1. **Understanding Viruses**: Begin by recognizing that viruses are microscopic infectious agents that can only replicate inside the living cells of an organism. They are significantly smaller than bacteria.

2. **Historical Context**: The question asks about the first virus to be purified. This refers to the process of isolating a virus from its host or environment for study.

3. **Identifying Candidates**: The video mentions several viruses: Flu virus, Tobacco virus, Smallpox virus, and Polio virus.

4. **Researching the Tobacco Virus**: The Tobacco Mosaic Virus (TMV) is known to be the first virus to be purified. It was isolated and characterized in the early 20th century, specifically in 1935 by Wendell Stanley.

5. **Conclusion**: Based on the information provided and historical context, the answer to the question is that the first virus to be purified was the Tobacco virus.

---