<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 23-year-old nulligravida presents for evaluation 5 weeks after her last menstrual period. Her previous menstruation cycle was regular, and her medical history is benign. She is sexually active with one partner and does not use contraception. A urine dipstick pregnancy test is negative. The vital signs are as follows: blood pressure 12080 mm Hg, heart rate 71min, respiratory rate 13min, and temperature 36.8C 98.2F. The physical examination is notable for breast engorgement, increased pigmentation of the nipples, and linea alba. The gynecologic examination demonstrates cervical and vaginal cyanosis.Measurement of which of the following substances is most appropriate in this case?? A: Blood estriol, B: Urinary human chorionic gonadotropin, C: Blood progesterone, D: Urinary estrogen metabolites, E: Blood human chorionic gonadotropin,  <response>: This is a question about evaluating a pregnant patient who is 5 weeks after her last menstrual period. The key findings in the stem are a negative urine pregnancy test but physical exam findings suggestive of early pregnancy like breast engorgement, increased nipple pigmentation, and cervicalvaginal cyanosis. The question asks which test is most appropriate to measure in this case. Based on the clinical scenario, we need a test that can reliably detect early pregnancy even if the urine test was negative. The choices given are different pregnancy hormones. Human chorionic gonadotropin hCG is produced by the placenta and is detectable very early in pregnancy. It would be the most appropriate test in this patient. Estriol, progesterone, and estrogen metabolites rise later in pregnancy and would not be as useful this early.E: Blood human chorionic gonadotropin 