Answer:
3.Treat the plasmid with DNA polymerase.
Step-by-step explanation:
DNA polymerase will not be useful in this step of the experiment.
In the third step of the experiment shown in the question above, it would be correct to use the enzyme called ligase, so that the plasmid was linked to the pine gene.
DNA polymerase cannot make this binding since the function of this enzyme is to allow DNA replication. As the polymerase was used in the third step of the experiment, the scientist will not succeed when trying to introduce the plasmid into bacterial cells, since this plasmid does not have the pine gene.