[Solved] About how many stars are visible to the naked eye on a clear, dark night away from city lights? A)a couple thousand B)a few hundred billion C)a few dozen D)several million Neural Tube Defect: A birth defect resulting from incomplete development of the brain, spinal cord, or their coverings. FAS: Fetal Alcohol Syndrome, a condition in a child that results from alcohol exposure during the mother's pregnancy, causing brain damage and growth problems. Human Chorionic Gonadotropin: A hormone produced by the placenta after implantation, often measured as a marker in pregnancy tests. Test: An examination or procedure done to detect or measure something, often used to diagnose diseases or conditions.