Correct Answer: C — APACHE II Score

ICU Severity Scoring Systems:

Score	Full Name	Use
APACHE II	Acute Physiology and Chronic Health Evaluation II	ICU mortality prediction (first 24h data)
SOFA	Sequential Organ Failure Assessment	Organ failure tracking, sepsis diagnosis
SAPS II	Simplified Acute Physiology Score II	ICU outcome prediction
CURB-65	—	Pneumonia severity (community setting)
GCS	Glasgow Coma Scale	Neurological status, not general ICU severity

APACHE II uses 12 physiological variables (temperature, MAP, HR, RR, oxygenation, pH, Na\(^+\), K\(^+\), creatinine, hematocrit, WBC, GCS) + age + chronic health points. Maximum score = 71; higher score = higher predicted mortality.