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 is used to maintain abstinence in alcohol dependence? 
Select and explain. 
A. Naltrexone, B. Clonidine, C. Disulfiram, D. Naloxone
A: Naltrexone
Answer: A: Naltrexone 
Explanation: None