A 32-year-old woman with a 6-month history of GERD presents to the emergency department with acute appendicitis. She is scheduled for emergency appendicectomy under general anesthesia. On examination, she is anxious, blood pressure 128/82 mmHg, heart rate 98/min, respiratory rate 18/min. She has not fasted for 8 hours. The anesthesiologist plans rapid sequence induction. Which of the following is the MOST appropriate choice for induction agent in this high-risk aspiration scenario?