<prompt> A 25-year-old pregnant woman, at 16 weeks of gestation, visits her obstetrician. A screening test suggests the possibility of a neural tube defect in her fetus. An ultrasound examination shows a 3-cm neural tube defect in the thoracic spine. The screening test that was administered to the mother measured serum levels of which of the following proteins?AlbuminAlpha-fetoproteinBilirubinChromogranin  <response>: Screening of pregnant women for serum AFP and examination by ultrasonography allow detection of virtually all anencephalic fetuses. Levels of the other proteins are not significantly affected by a neural tube defect in the fetus.Diagnosis: Neural tube defect, spina bifida 