You are answering a USMLE-style medical question. Question: A 2,300 g (5 lb) male newborn is delivered to a 29-year-old primigravid woman. The mother has HIV and received triple antiretroviral therapy during pregnancy. Her HIV viral load was 678 copies/mL 1 week prior to delivery. Labor was uncomplicated. Apgar scores were 7 and 8 at 1 and 5 minutes respectively. Physical examination of the newborn shows no abnormalities. Which of the following is the most appropriate next step in the management of this infant? Options: A) Administer zidovudine B) HIV DNA testing C) HIV RNA testing D) Reassurance and follow-up Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.