In the above represented plasmid, an alien piece of DNA is inserted at EcoRI site. Which of the following strategies will be chosen to select the recombinant colonies?

The correct answer is that white-colored colonies will be selected. Since an alien piece of DNA is being inserted at EcoRI site, the gene $\beta$-galactosidase present here will undergo insertional inactivation. This gene is responsible for producing blue-colored colonies, but since it has been insertionally inactivated, white colored colonies will be produced. Ampicillin and tetracycline resistance genes present in the given DNA will remain intact. Thus, the given DNA will show amp ${ }^R$ and tet ${ }^R$.