You Isolate a Pathogenic Strain of E

Multiple Choice

You isolate a pathogenic strain of E.coli from a patient and discover that this E.coli strain is resistant to an antibiotic.Common laboratory strains of E.coli are not resistant to this antibiotic, nor are any other previously isolated pathogenic E.coli strains.However, such resistance has been observed in other bacteria in the hospital in which the patient was treated.This newly discovered antibiotic resistance in E.coli is most likely due to

A) a mutation within a gene.
B) a mutation within the regulatory DNA of a gene.
C) gene duplication.
D) horizontal gene transfer.