Sometimes engineers increase output through crossbreeding. This is when
they:
A. combine two plants so that each plant's strength compensates for
the other's weakness.
B: genetically alter the DNA of a plant to produce a desired trait.
C. cultivate a variety of plants in one area so that cross
contamination does not occur.
D. cultivate a variety of plants in one area so that one pest does not
destroy all the crops.