A researcher has a laboratory strain of flies that have loss-of-function mutations in both gene X and white. These flies are used as hosts for P element transformation: Embryos of the double mutant strain are injected with two plasmids, one containing a wild-type copy of the white gene (w+) and a wild-type copy of gene X, side-by-side within P element inverted repeats, and the other plasmid containing only the P element transposase gene. Transgenic offspring of the injected flies will Select one:
a. have both plasmids integrated randomly into the genome.
b. have white eyes and express transposase.
c. have red eyes and a wild-type copy of gene X in place of the mutant copy in their genome.
d. have red eyes and a wild-type copy of gene X integrated into a random location in the genome.

d. have red eyes and a wild-type copy of gene X integrated into a random location in the genome.

Explanation:

P elements are genetic mobile elements, i.e., transposons, which are highly mobile in the Drosophila germline. These transposons naturally cause a high rate of mutation in Drosophila germline cells resulted from an interstrain cross of males with autonomous P elements and females without P elements, a phenomenon known as hybrid dysgenesis. Moreover, a transposase in an enzyme required for the mechanism of transposition (in this case, to mediate the transposition of P elements which are reinserted randomly). The P elements have provided a useful mutagenesis system widely used in molecular biology and genetics research. In fly transformation, it is required to use plasmids with a P element (P plasmids) which contains a w+ (red-eye) marker and recognition sequences for the transposase. In this case, the embryos injected with P plasmids will contain all the components to insert the reporter gene (red-eye marker) and the wild-type copy of gene X into a random site of the genome.