This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
Which of the following drugs does not activate opioid receptors, has been proposed as a drug in the management of opioid addiction and with just a single dose blocks the action of injected heroin for up to 48 hours? 
Select and explain. 
A. Amphetamine, B. Buspirone, C. Methadone, D. Naltrexone
D: Naltrexone
Answer: D: Naltrexone 
Explanation: (Ref: KDT 6/e p437) Naltrexone is a long acting, orally effective opioid antagonist that can be used as the maintenance treatment of opioid addicts. It is also used to decrease the craving for alcohol.