The DNA fragments separated on an agarose gel can be visualised after staining with:

Options

A. Bromophenol blue
B. Acetocarmine
C. Aniline blue
D. Ethidium bromide

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks about the visualization of DNA fragments that have been separated using agarose gel electrophoresis. This is a common technique used in molecular biology to separate DNA based on size.

2. **Identifying the Purpose of Staining**: After the DNA fragments are separated on the agarose gel, they need to be stained in order to visualize them. This is crucial because DNA is not visible under normal light.

3. **Reviewing the Options**: The options provided are:
- Bromophenol blue
- Acetylcaramide
- Aniline blue
- Ethidium bromide

4. **Analyzing Each Option**:
- **Bromophenol Blue**: This is primarily used as a tracking dye during electrophoresis to monitor the progress of the DNA migration but does not effectively stain DNA for visualization.
- **Acetylcaramide**: This is not commonly used for DNA visualization.
- **Aniline Blue**: This is used for staining proteins and does not specifically stain DNA.
- **Ethidium Bromide**: This is a fluorescent dye that intercalates between the base pairs of DNA. When exposed to UV light, it emits fluorescence, allowing for the visualization of DNA bands.

5. **Conclusion**: Based on the analysis, the correct answer to the question is **Ethidium Bromide**, as it is specifically used for visualizing DNA fragments after they have been separated on an agarose gel.

**Final Answer**: Ethidium Bromide

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