**Core Concept**
Bupropion is a non-nicotine prescription medication used to help individuals quit smoking by managing withdrawal symptoms and cravings. It is a norepinephrine-dopamine reuptake inhibitor (NDRI), which increases the levels of these neurotransmitters in the brain, thereby reducing the urge to smoke.

**Why the Correct Answer is Right**
Bupropion works by affecting the brain's reward system, which is responsible for nicotine addiction. By increasing the levels of norepinephrine and dopamine, bupropion helps to reduce the symptoms of nicotine withdrawal, such as irritability, anxiety, and depression, making it easier for individuals to quit smoking. This is different from nicotine replacement therapy (NRT) or non-nicotine prescription medications like varenicline, which directly target the nicotine receptors in the brain.

**Why Each Wrong Option is Incorrect**
**Option A:** Naltrexone is an opioid antagonist used to treat opioid addiction, not smoking cessation. It works by blocking the effects of opioids at the mu receptor, which has no relevance to nicotine addiction.
**Option C:** Buprenorphine is a partial opioid agonist used to treat opioid addiction, not smoking cessation. It binds to the mu receptor, but with a lower affinity than full opioid agonists, reducing the risk of overdose and withdrawal symptoms.
**Option D:** Methadone is a full opioid agonist used to treat opioid addiction, not smoking cessation. It has a high potential for abuse and dependence, which is not suitable for smoking cessation.

**Clinical Pearl / High-Yield Fact**
Bupropion is also used off-label to treat major depressive disorder, seasonal affective disorder, and attention deficit hyperactivity disorder (ADHD). Its unique mechanism of action as an NDRI makes it a valuable treatment option for various psychiatric conditions.

**✓ Correct Answer: B. Bupropion**