A 24-year-old female presents to the emergency department after ingesting an unknown quantity of acetaminophen approximately 6 hours ago. She is asymptomatic, and initial labs show a serum acetaminophen level that is above the probable toxicity line on the Rumack-Matthew nomogram. What is the most appropriate next step in management?

✓ Correct Answer: Option B

N-acetylcysteine (NAC) is the antidote for acetaminophen overdose and should be administered if the serum level is above the probable toxicity line on the Rumack-Matthew nomogram, especially if within 8 hours of ingestion. Activated charcoal is only effective within 1-2 hours of ingestion. Delaying treatment increases the risk of hepatotoxicity.