Which chemical is used to precipitate out the purified DNA during the isolation of genetic material?

Chilled ethanol

Chilled ethanol (or isopropanol) is commonly used to precipitate purified DNA during the process of isolating genetic material.

When DNA is mixed with chilled ethanol, the DNA molecules become less soluble in the alcohol, causing them to precipitate out of the solution. This allows for the separation and collection of the DNA from the rest of the components in the mixture. Ethidium bromide and bromophenol blue are not used for precipitating DNA during genetic material isolation; rather, they serve other purposes in molecular biology techniques (such as staining DNA in gels or as tracking dyes). Therefore, the correct answer is "B. Chilled ethanol."