In rDNA technology, the selection of white colonies of bacteria in the presence of chromogenic substrate is possible because of
(A) insertional inactivation of B-galactosidase in recombinant bacteria
(B) presence of the ß-galactosidase gene in recombinant bacteria
(C) insertional inactivation of B-galactosidase in non-recombinant bacteria
(D) inactivation of glycosidase enzyme in recombinant bacteria