The correct option is D vector
Vector is a DNA molecule that carries a foreign DNA segment and replicates inside a host cell. Therefore a vector not only carries the gene to the host, it also clones it inside the host cell. The vector DNA and foreign DNA carrying gene of interest are cut by the same restriction endonuclease enzyme to produce complementary sticky ends. With the help of DNA ligase enzyme, the complementary sticky ends of the two DNAs are joined to produce a recombinant DNA (rDNA), which is then introduced into the host cell.