Which of the following stains is commonly used as a post-stain?

Fast Blast is commonly used as a post-stain because it is specifically designed for visualizing DNA in agarose gels after electrophoresis. This stain provides a clear and effective means to assess the presence and quantity of DNA bands within the gel, making it easier for researchers to analyze their results.

In the context of post-staining techniques, Fast Blast binds to the DNA and emits a strong color when exposed to specific wavelengths of light, which enhances the visibility of DNA bands. This is particularly important in gel electrophoresis, where clear identification of the separated DNA fragments is necessary for interpretation of experimental outcomes.

The other options, while useful in different contexts, do not serve as post-stains in the same manner. For instance, Syber Green and Ethidium bromide are commonly used during the DNA amplification process or for intercalating with DNA during PCR, but they are not primarily used for post-staining agarose gels. EZ Vision serves a similar purpose to Fast Blast but may not be as widely recognized or traditionally utilized as a primary post-stain in common lab practices. Thus, the choice of Fast Blast emphasizes its established role and effectiveness in post-experimental analysis for DNA visualization.