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: Anaesthesia
Opioid antagonist that can be given orally – 
Select and explain. 
A. Naltrexone, B. Naloxone, C. Nalbuphene, D. Pentazocine
A: Naltrexone
Answer: A: Naltrexone 
Explanation: Amongst opioid antagonists :- Naloxone is given iv or im, Nalmefene is given iv, im or sc, and Naltrexone is given orally.