A patient who is taking immunosuppressants develops a urinary tract infection. The causative ...

A patient who is taking immunosuppressants develops a urinary tract infection. The causative organism is sensitive to sulfonamides and to another, more expensive antibiotic. The prescriber orders the more expensive antibiotic.
 
  The nursing student assigned to this patient asks the nurse why the more expensive antibiotic is being used. Which response by the nurse is correct?
  a. Immunosuppressed patients are folate deficient.
  b. Patients who are immunosuppressed are more likely to develop resistance.
  c. Sulfonamides are bacteriostatic and depend on host immunity to work.
  d. Sulfonamides intensify the effects of immunosuppression.