Viruses were first crystallized and isolated by

Options

A. Ivanowsky
B. Bawden
C. W.M. Stanley
D. Smith

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks who was the first scientist to crystallize and isolate viruses. We need to identify the correct scientist from the given options.

2. **Reviewing the Options**: The options provided are:
- A. Iwanowski
- B. Baudin
- C. W. M. Stanley
- D. Smith

3. **Historical Context**:
- Dmitry Ivanovsky is known for his early work with viruses in 1892, where he coined the term "virus," meaning "poisonous fluid."
- M. W. Beijerinck later contributed to the understanding of viruses in 1898, referring to them as "contagium vivum fluidum," indicating that they are infectious living fluids.

4. **Identifying the Key Scientist**:
- In 1935, W. M. Stanley became the first scientist to crystallize a virus. He discovered that the crystals of the virus were primarily composed of protein.

5. **Conclusion**: Based on the historical contributions of these scientists, the correct answer to the question "Viruses were first crystallized and isolated by" is C. W. M. Stanley.

**Final Answer**: C. W. M. Stanley

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