39. A plasmid that encodes resistance to ampicillin and tetracycline is digested with the restriction enzyme Sall, which cuts the plasmid at a single site in the tetracycline-resistance gene. The DNA is then annealed with a Sall digest of human DNA, ligated, and used to transform E. coli cells. What antibiotic would you put in an agar plate to ensure that the cells of a bacterial colony contain the plasmid? (A) Ampicillin. (B) Tetracycline. (C) Ampicillin and tetracycline. (D) Any antibiotic will do. (E) The agar plate should not contain any antibiotic.