You are answering a USMLE-style medical question. Question: A previously healthy 30-year-old woman comes to the physician for the evaluation of pain during sexual intercourse for 6 months. She also reports frequent episodes of crampy pelvic pain that starts one day before menses and lasts for 7 days. Her symptoms are not relieved with pain medication. Menses occur at regular 28-day intervals and last 5 days. Her last menstrual period was 2 weeks ago. She is sexually active with her husband. She uses a combined oral contraceptive pill. Her vital signs are within normal limits. Physical examination shows rectovaginal tenderness. Cervical and urethral swabs are negative. Transvaginal ultrasonography shows no abnormalities. Which of the following is the most appropriate next step in management? Options: A) Measurement of CA-125 levels B) Hysterectomy C) Laparoscopy D) Hysteroscopy Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.