Ans.
Gene targeting or gene replacement strategy is defined as a genetic technique that involves use of homologous recombination and replacement of a gene with another gene. It can be used for the removal of exons, deletion of a gene, or addition of new gene.
Gene knockout shows removal or exchange of a gene with a inactive or mutated copy of that gene to create individual with a new trait. Therefore, to turn off the gene Insom, the original Insom gene will be replace with a mutated, inactivated copy of Insom.
Thus, the correct answer is option). A.