Gel electrophoresis is employed in .
I. Separation of DNA fragmetns .
II. Selection of DNA fragments .
III. Vissualizing DNA
IV. Check the progression of restriction enzyme digestion.

Options

A. I & II
B. II&III
C. III &IV
D. I &IV

Answer

**Step-by-Step Solution:**

1. **Understanding Gel Electrophoresis**: Gel electrophoresis is a technique used to separate DNA fragments based on their size. It involves placing DNA samples in an agarose gel and applying an electric current, which causes the negatively charged DNA to migrate towards the positive electrode.

2. **Analyzing the Options**:
- **I. Separation of DNA fragments**: This is correct. Gel electrophoresis is primarily used for separating DNA fragments of different sizes.
- **II. Selection of DNA fragments**: This is incorrect. Selection typically involves using selective markers or other techniques, not gel electrophoresis.
- **III. Visualizing DNA**: This is partially correct. While gel electrophoresis allows for visualization of DNA fragments after staining (e.g., with ethidium bromide), the technique itself does not visualize DNA without additional steps.
- **IV. Check the progression of restriction enzyme digestion**: This is correct. Gel electrophoresis can be used to check whether restriction enzymes have digested the DNA properly by observing the resulting fragment sizes.

3. **Conclusion**: Based on the analysis, gel electrophoresis is employed in:
- I (Separation of DNA fragments)
- IV (Check the progression of restriction enzyme digestion)

Thus, the correct answer is options I and IV.

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