This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Medicine
Oliguria is defined as urine output - 
Select and explain. 
A. <0.5ml/hr, B. 10ml/hr, C. 20ml/hr, D. 40ml/hr
A: <0.5ml/hr
Answer: A: <0.5ml/hr 
Explanation: Oliguria or hypouresis is the low output of urine specifically more than 80 ml/day but less than 400ml/day. The decreased output of urine may be a sign of dehydration, kidney failure, hypovolemic shock, HHNS hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary obstruction/urinary retention, DKA, pre-eclampsia, and urinary tract infections, among other conditions Normal: 1 - 2ml/kg/hr. Oliguria: <1.0ml/kg/hr. Anuria: no urine output. Polyuria: > 3ml/kg/hr. Older children: 30 ml/hr is the minimum normal output. Ref Harrison20th edition pg 277