DNA precipitation out of a mixture of biomolecules can be achieved by treatment with chilled ethanol, isopropanol, chilled chloroform, or methanol at room temperature?

Correct option is B. Isopropanol. During the isolation of a desired gene, isopropanol is used for the precipitation of DNA. Chilled ethanol is also frequently used but isopropanol is more efficient. So, the correct answer is 'isopropanol'.