question: Q:A 23-year-old male presents with complaints of polydipsia and frequent, large-volume urination. Laboratory testing does not demonstrate any evidence of diabetes; however, a reduced urine osmolality of 120 mOsm/L is measured. Which of the following findings on a desmopressin test would be most consistent with a diagnosis of central diabetes insipidus?? 
  {'A': 'Reduction in urine osmolality to 60 mOsm/L following vasopressin administration', 'B': 'Reduction in urine osmolality to 110 mOsm/L following vasopressin administration', 'C': 'Increase in urine osmolality to 130 mOsm/L following vasopressin administration', 'D': 'Increase in urine osmolality to 400 mOsm/L following vasopressin administration', 'E': 'No detectable change in urine osmolality following vasopressin administration'},