**Core Concept**
Opioid poisoning, also known as opioid overdose, is a life-threatening medical emergency caused by the ingestion of excessive amounts of opioids, leading to respiratory depression, sedation, and potentially death. The treatment of choice involves administering an antidote that reverses the effects of opioids on the central nervous system.

**Why the Correct Answer is Right**
Naloxone is a potent opioid antagonist that competitively binds to opioid receptors in the brain and spinal cord, rapidly reversing the effects of opioids, including respiratory depression. By blocking the opioid receptors, naloxone restores normal respiratory function, allowing the patient to breathe normally. Naloxone is the treatment of choice for opioid poisoning because of its rapid onset of action, ease of administration, and high efficacy.

**Why Each Wrong Option is Incorrect**
**Option A:** Naloxone is the correct answer, not a combination of medications or a specific medication like acetylcysteine, which is used to treat acetaminophen overdose.
**Option B:** Benzodiazepines, such as diazepam, are actually contraindicated in opioid poisoning as they can worsen respiratory depression.
**Option C:** Activated charcoal is not effective in treating opioid poisoning, as it cannot bind to the opioid molecule in the gastrointestinal tract.
**Option D:** Flumazenil is a benzodiazepine antagonist, not an opioid antagonist, and is not used to treat opioid poisoning.

**Clinical Pearl / High-Yield Fact**
Naloxone is a reversible opioid antagonist that should be administered in small doses (0.4-2 mg IV) and titrated to effect, as it can cause withdrawal symptoms in individuals with chronic opioid use.

**Correct Answer:** C. Naloxone