Answer:
option A
Explanation:
In carrying out these experimental procedure, the same restriction enzyme that is used to cut out the gene of interest should also be the same used for the cutting of the plasmid to generate sticky ends. Then the desired gene is inserted into the cut plasmid then treatment with DNA ligase. Purified DNA ligase is utilized in gene cloning to join/ligate DNA molecules together forming a recombinant DNA. Thus, step 3 should be carried out after step 4.
