You are answering a USMLE-style medical question. Question: A 25-year-old woman presents to her primary care provider for evaluation of a "painful mass in my left groin." She says that her symptoms began 4 days ago as a painful mass that slowly enlarged, ruptured, and ulcerated. However, she denies fever, chills, dysuria, or hematuria. Three weeks prior to her current symptoms she noted a small, painless ulcer on her labium majorum that resolved after a few days. She admits to having unprotected sex with a male partner a month ago while she was traveling in Southeast Asia. Temperature is 99°F (37.2°C), blood pressure is 139/84 mmHg, pulse is 76/min, and respirations are 18/min. Physical examination is significant for left-sided, tender, ulcerative lymph nodes with a dark discoloration. Which of the following is most likely to be seen in this patient's condition? Options: A) Gram-negative rods in school of fish formation on Gram stain B) PCR positive for Chlamydia trachomatis C) Positive RPR, VDRL, and FTA-ABS D) Tzanck smear with multinucleated giant cells Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.