A nurse is caring for a 68-year-old male client admitted to the intensive care unit. What is the priority nursing intervention for this client?

Choice A rationale: Vasopressors increase vascular tone but are not first-line; hypovolemia must be corrected with fluids before pharmacologic support to restore adequate perfusion. Choice B rationale: Oxygen therapy is already initiated; hypoxemia is secondary to poor perfusion, so correcting circulation with fluids is the priority before escalating oxygen support. Choice C rationale: Antibiotics treat infection but do not immediately correct hypoperfusion; fluid resuscitation must precede antimicrobial therapy to stabilize circulation and prevent shock progression. Choice D rationale: IV fluids restore intravascular volume, improve perfusion, and correct hypotension, making fluid resuscitation the priority intervention in septic shock with hypovolemia.