In clinical practice, anuria is defined as urine output of:

Correct option is C

Anuria is defined as urine output <100 ml/24 hrs. Oliguria is 100–400 ml/day, and normal urine output is 800–2000 ml/day.
Explanation of options: (a) ✘ <400 ml = oliguria, not anuria. (b) ✘ <200 ml = still oliguria, not strict definition. (c) ✔ Correct; <100 ml/24 hr = anuria. (d) ✘ <50 ml is extreme anuria, but cutoff is <100 ml.