A bacterium called Bacillus thuringiensis contains a protein that can kill cotton ballworms and certain other kinds of caterpillars. A different bacterium called Agrobacterium tumefaciens has the ability to insert its genetic material into plants. Scientists in the late twentieth century took a gene from Bacillus thuringiensis and inserted it into specimens of Agrobacterium tumefaciens. Genetic material from the Agrobacterium tumefaciens specimens was then inserted into cotton plants. The goal of these tests was to reduce caterpillar infestation in the cotton plants.

These tests are an example of
A.
natural selection.
B.
creating purebred species.
C.
meiotic cell division.
D.
genetic modification.