Final answer:
Option (c), The prenatal test commonly done between the 15th and 18th weeks of pregnancy is amniocentesis. It involves sampling amniotic fluid to test for genetic disorders, with advice from genetic counselors.
Step-by-step explanation:
Prenatal Testing Between the 15th and 18th Weeks of Pregnancy
The form of prenatal testing that is most commonly performed between the 15th and 18th week of pregnancy is amniocentesis. During amniocentesis, a small amount of amniotic fluid is extracted from the sac surrounding the fetus for testing. The fluid contains fetal cells, which are then analyzed for genetic abnormalities. This procedure helps to diagnose genetic disorders that can be inherited and is typically recommended for parents who have a genetic disorder in their family or are at risk of passing on genetic disorders to their children. It's advised under the guidance of genetic counselors.
Prenatal genetic diagnosis (PGD) refers to the screening of embryos during in vitro fertilization, whereas amniocentesis is a procedure done once a fetus has developed within the mother's uterus. It's important for parents to understand the different stages of prenatal development including the germinal, embryonic, and fetal stages, and that various genetic testing options like DNA tests, chorionic villus sampling, and blood tests are available depending on the stage of pregnancy and condition being tested for.