question: Q:A 71-year-old man with colorectal cancer comes to the physician for follow-up examination after undergoing a sigmoid colectomy. The physician recommends adjuvant chemotherapy with an agent that results in single-stranded DNA breaks. This chemotherapeutic agent most likely has an effect on which of the following enzymes?? 
  {'A': 'Telomerase', 'B': 'Topoisomerase II', 'C': 'Helicase', 'D': 'DNA polymerase III', 'E': 'Topoisomerase I'},