Answer: b. Further testing will be required to confirm any diagnosis.
Step-by-step explanation:
The certain blood screening tests are just presumptive test for suspecting a defect or disorder in the prenatal life. These tests are not definitive in nature and further diagnosis is required to confirm them for example, amniocentesis.
In the given situation, the couple which is waiting for the results of blood tests suspecting potential Down syndrome and other prenatal defects must be educated with the fact that further tests are required to confirm the results of the tests. These will include the confirmatory diagnostic tests.