You are answering a USMLE-style medical question. Question: A four-day-old neonate is brought to the pediatrician with vaginal discharge for the last two days. Her mother is concerned about the blood-tinged discharge but states that her daughter has been feeding and voiding well. The neonate was delivered at 39 weeks gestation by an uncomplicated vaginal delivery, and she and her mother were discharged home after two days. The prenatal course was complicated by chlamydia in the mother during the first trimester, for which she and the partner were both treated with a negative test of cure. The neonate’s biological father is no longer involved the patient's care, but her mother’s boyfriend has been caring for the baby whenever the mother rests. At this visit, the neonate’s temperature is 98.5°F (36.9°C), pulse is 138/min, and respirations are 51/min. She appears comfortable, and cardiopulmonary and abdominal exams are unremarkable. There are no bruises or marks on her skin. Examination of the genitals reveals no vulvar irritation or skin changes, but there is scant pink mucoid discharge at the introitus. Which of the following is the best next step in management? Options: A) Vaginal exam under anesthesia B) Vaginal culture C) Warm water irrigation of the vagina D) Reassurance Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.