<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 36-year-old primigravid woman at 15 weeks gestation comes to the physician for a routine prenatal visit. She has not been taking prenatal vitamins and admits to consuming alcohol regularly. Pelvic examination shows a uterus consistent in size with a 15-week gestation. A quadruple screening test shows markedly elevated maternal serum α-fetoprotein. Maternal serum concentrations of β-human chorionic gonadotropin, estriol, and inhibin A are normal. Which of the following is the most likely explanation for these findings?? A: Fetal alcohol syndrome, B: Trisomy 21, C: Holoprosencephaly, D: Spina bifida cystica, E: Trisomy 18,  <response>: This is a question about interpreting prenatal screening results in a pregnant woman with risk factors. The key findings are an elevated AFP level on quadruple screening, with normal levels of the other markers hCG, estriol, inhibin A. AFP is made by the fetus and elevated levels may indicate a neural tube defect like spina bifida. The history of alcohol use raises concern for fetal alcohol syndrome, but this would not elevate AFP. Trisomy 21, 18 and holoprosencephaly may affect other markers but not isolated AFP elevation. Therefore, the most likely explanation is a neural tube defect like spina bifida.D: Spina bifida cystica 