This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Which of the following is the best parameter to assess fluid intake in. Polytrauma patient 
Select and explain. 
A. Urine output, B. Blood pressure, C. Pulse, D. Pulse oximetry
A: Urine output
Answer: A: Urine output 
Explanation: The urine output is an impoant clinical parameter of renal function and blood volume status, especially in critically ill multiple trauma patients. In the present study, the minute-to-minute urine flow rate and its variability were analyzed in hypotensive multiple trauma patients during the first 6 h of their ICU stay. It is used to assess the tissue perfusion