This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following statements regarding naltrexone are true ? 
Select and explain. 
A. It is an opioid antagonist, B. It is used in alcohol dependence, C. It is used to treat opioid dependence, D. All of these
D: All of these
Answer: D: All of these 
Explanation: None