For excel:
you plan to use the fill down feature on a formula and you need to keep a cell reference the same. which one of the following formats will allow you to keep the same cell reference?

Which best describes the role or restriction enzymes in the analysis of edna a. to break dna into fragments that vary in size so they can be sorted and analyzed b. to amplify small amounts of dna and generate large amounts of dna for analysis c. to purify samples of dna obtained from the environment so they can be analyzed d. to sort different sizes of dna fragments into a banding pattern that can be analyzed