Molecular explanation for transformation was given by:

Options

A. Griffith
B. Avery, Mc Carty and Mc Leod
C. Lederberg and Tatum
D. Avery and Mc Carty

Answer

To answer the question regarding who provided the molecular explanation for transformation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Transformation**:
- Transformation is a process where genetic material is transferred from one bacterium to another, resulting in a change in the recipient's characteristics.

2. **Griffith's Experiment**:
- Frederick Griffith conducted experiments in the 1920s that demonstrated transformation in bacteria. He showed that non-virulent bacteria could become virulent when exposed to heat-killed virulent bacteria. However, Griffith did not identify the molecular basis of this transformation.

3. **Avery, McCarty, and MacLeod's Contribution**:
- In 1944, scientists Oswald Avery, Colin MacLeod, and Maclyn McCarty conducted further experiments to identify the substance responsible for transformation. They concluded that DNA, not protein, was the transforming substance that carried genetic information.

4. **Significance of Their Work**:
- Their work provided the first clear molecular explanation of how genetic information could be transferred between bacteria, establishing DNA as the genetic material.

5. **Conclusion**:
- Therefore, the molecular explanation for transformation was given by Avery, McCarty, and MacLeod in 1944, and they are credited with the discovery of the "Transforming Principle."

### Final Answer:
The molecular explanation for transformation was given by Avery, McCarty, and MacLeod in 1944.

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