question: Q:A 33-year-old woman presents to the urgent care center with 4 days of abdominal pain and increasingly frequent bloody diarrhea. She states that she is currently having 6 episodes of moderate volume diarrhea per day with streaks of blood mixed in. Her vital signs include: blood pressure 121/81 mm Hg, heart rate 77/min, and respiratory rate 15/min. Physical examination is largely negative. Given the following options, which is the most likely pathogen responsible for her presentation?? 
  {'A': 'Clostridium difficile', 'B': 'Campylobacter', 'C': 'E. coli 0157:H7', 'D': 'Salmonella', 'E': 'Shigella'},