If bacteria transformed with a recombinant pUC18 plasmid produce white colonies when grown on plates containing ampicillin and Xgal, which of the following is least likely? a. They produce β-lactamase that provides resistance to ampicillin.
b. They carry a vector that contains a DNA fragment inserted into the multiple cloning site.
c. They produce functional β-galactosidase that cleaves X-gal.
d. They carry a vector with a lacZ gene that has been disrupted and rendered nonfunctional.
e. They carry a vector with the bla gene used as the selectable marker.