The correct option is D A recombinant DNA is inserted within the coding sequence of enzyme β-galactosidase
Insertional inactivation is the property used for screening of recombinant colonies.
In recombinant DNA technology, a gene of interest is inserted into a plasmid which is taken up by competant cells.
In this case, as the cloning site is in the middle of the beta-galactosidase gene. The gene of interest is inserted within the cloning site inside the beta-galactosidase gene. The gene thus gets disrupted. So, it is inactivated due to the insertion of the gene of interest. This is called insertional inactivation.