You are answering a USMLE-style medical question. Question: A 24-year-old G2P1 woman at 39 weeks’ gestation presents to the emergency department complaining of painful contractions occurring every 10 minutes for the past 2 hours, consistent with latent labor. She says she has not experienced vaginal discharge, bleeding, or fluid leakage, and is currently taking no medications. On physical examination, her blood pressure is 110/70 mm Hg, heart rate is 86/min, and temperature is 37.6°C (99.7°F). She has had little prenatal care and uses condoms inconsistently. Her sexually transmitted infections status is unknown. As part of the patient’s workup, she undergoes a series of rapid screening tests that result in the administration of zidovudine during delivery. The infant is also given zidovudine to reduce the risk of transmission. A confirmatory test is then performed in the mother to confirm the diagnosis of HIV. Which of the following is most true about the confirmatory test? Options: A) It is a Southwestern blot, identifying the presence of DNA-binding proteins B) It is a Northern blot, identifying the presence of RNA C) It is a Northern blot, identifying the presence of DNA D) It is an HIV-1/HIV2 antibody differentiation immunoassay Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.