C

Norepinephrine is the first-line vasopressor in septic shock and its efficacy is judged by whether it raises and maintains the target mean arterial pressure (typically ≥ 65 mm Hg); a rise in heart rate or a fall in urine output are not primary response indicators [Leone, 2015, PMID 25888071; Beale, 2004, PMID 15542956].