57. Of these steps, which one occurs earliest in the process of producing recombinant DNA?
(A) Human DNA fragments are mixed with the cut plasmids.
(B) The same restriction enzyme is used to isolate the gene of interest and to cut the plasmid DNA.
(C) Bacteria bearing the plasmid of interest are treated with antibiotics.
(D) The recombinant plasmids are mixed with bacteria.
(E) Bacteria carrying recombinant plasmids are cloned.