During her twelfth week of gestation, 38-year-old Merlia underwent a procedure in which a small sample of cells from the placenta was taken for screening. This was done to detect if the fetus had any genetic disorder. This procedure is called ________.

A) chorionic villus sampling
B) amniocentesis
C) neural tube defect screening
D) alpha-fetoprotein sampling

Chorionic villus sampling (CVS) is a procedure in which a small sample of cells from the placenta is taken for prenatal genetic testing. The procedure is usually performed between 10 and 13 weeks of pregnancy and can detect genetic disorders such as Down syndrome, cystic fibrosis, and sickle cell anemia. Amniocentesis is another prenatal genetic testing procedure, but it is typically performed later in pregnancy (usually between 15 and 20 weeks). Neural tube defect screening and alpha-fetoprotein sampling are screening tests for specific birth defects or conditions, but they do not involve taking a sample of placental tissue.