A little more context would be helpful, but in general Gram Staining helps us to decipher between two major groups of bacteria (Gram positive and Gram Negative). This is helpful because different antibiotics must be used to treat infections from the different types of bacteria, so it will help them to properly medicate Anna.
All of the answers would be correct,
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The answer is D. For producing recombinant, first you need to cut the insert part and vector part to get the same end by using restriction enzyme. Then using DNA ligase to bind these two parts to get a new plasmids.