This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Shock is clinically best assessed by - 
Select and explain. 
A. Urine output, B. CVP, C. BP, D. Hydration
A: Urine output
Answer: A: Urine output 
Explanation: • Shock: Inadequate delivery of oxygen and nutrients due to poor tissue perfusion to maintain normal tissue and cellular function
• Mean arterial pressure <60 mm Hg in previously normotensive patients
• Systemic vascular resistance rises leading to decreased cutaneous blood flow and autoregulation is critical in sustaining cerebral and coronary blood flow.