question: Q:An 18-year old college freshman presents to his university clinic because he has not been feeling well for the past two weeks. He has had a persistent headache, occasional cough, and chills without rigors. The patient’s vital signs are normal and physical exam is unremarkable. His radiograph shows patchy interstitial lung infiltrates and he is diagnosed with atypical pneumonia. The patient is prescribed azithromycin and takes his medication as instructed. Despite adherence to his drug regimen, he returns to the clinic one week later because his symptoms have not improved. The organism responsible for this infection is likely resistant to azithromycin through which mechanism?? 
  {'A': 'Presence of a beta-lactamase', 'B': 'Insertion of drug efflux pumps', 'C': 'Decreased binding to RNA polymerase', 'D': 'Mutation in topoisomerase II', 'E': 'Methylation of ribosomal binding site'},