Answer: D. they're carriers of a genetic disorder,
Step-by-step explanation:
Genetic testing also known as testing of the genetic material which is DNA in humans so as to determine the diseases and disorders associated with bloodline relatives of a single individual. It studies the pedigree chart of the family of the person under consideration for this test.
It is done before becoming pregnant or the couple desire to have a child naturally. Both parents are tested and their family history of diseases and disorders is also examined so as to know the possibilities of transmission of the diseases and disorders they inherited may also get passed on to the children.