12. All of the following statements are true except: (A) Col plasmids encode colicin which kills strains of E. coli. (B) Plasmids which carry genes encoding degradative enzymes for pesticides are called metabolic plasmids. (C) All bacteriocin genes are on plasmids. (D) R factors have genes for resistance to antibiotics and these resistance genes are often within transposons. (E) F factor of E.coli is both a conjugative plasmid and an episome.