Hallmark of the Watson and Crick three dimensional DNA model was based upon the findigs of

Options

A. Wilkins and Franklin
B. Erwin charagaff
C. Hershey and Chase
D. Meselson and Stahl

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the findings that served as the basis for the Watson and Crick three-dimensional DNA model.

2. **Identifying Key Contributors**: Watson and Crick proposed the double helix structure of DNA, which is a significant milestone in genetics. To understand their model, we need to identify the scientists whose findings contributed to this model.

3. **Analyzing the Options**:
- **Option 1: Wilkins and Franklin**: These scientists conducted X-ray diffraction studies that provided crucial data about the helical structure of DNA. Their work was instrumental in Watson and Crick's development of the DNA model.
- **Option 2: Erwin Chargaff**: He formulated Chargaff's rules, which state that in double-stranded DNA, the amount of adenine equals thymine and the amount of guanine equals cytosine. While this information is relevant, it did not directly lead to the 3D model.
- **Option 3: Hershey and Chase**: Their experiments confirmed that DNA is the genetic material, but this finding is not related to the structural model proposed by Watson and Crick.
- **Option 4: Meselson and Stahl**: They provided evidence for the semi-conservative replication of DNA, which is important but not directly related to the structure of DNA.

4. **Conclusion**: Based on the analysis, the hallmark of the Watson and Crick three-dimensional DNA model was primarily based on the findings of **Wilkins and Franklin** (Option 1). Their X-ray diffraction data was critical in elucidating the helical structure of DNA.

### Final Answer:
The hallmark of the Watson and Crick three-dimensional DNA model was based upon the findings of **Wilkins and Franklin**.

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