Q. A 28-year-old female presents to the emergency department with complaints of severe lower abdominal pain that has been progressively worsening over the past 24 hours. She reports a history of irregular periods, but denies any recent missed periods. On physical examination, her vital signs are within normal limits, and her abdomen is tender to palpation, with rebound tenderness and guarding. Based on her symptoms and examination findings, you suspect a possible ectopic pregnancy and promptly order a pregnancy test, which returns positive. An ultrasound is then performed (see image), which reveals a gestational sac with a fetal pole located outside of the uterus, confirming the diagnosis. The patient is immediately started on intravenous fluids and given pain medication for relief. Given the high risk of rupture and bleeding, the decision is made to initiate treatment with a medication that will halt the growth of the developing embryo and cause it to be reabsorbed by the body. Which of the following medications is the best choice for this patient?