This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inhalational Anesthetic Agents, Subject name: Anaesthesia
Which is wrong regarding entonox? 
Select and explain. 
A. Is used for labor analgesia, B. Is a mixture of nitrous Oxide and oxygen in the ratio of 50: 50, C. Pin index is 7, D. Can be used for anesthesia
D: Can be used for anesthesia
Answer: D: Can be used for anesthesia 
Explanation: Entonox is used for analgesia not anesthesia. Entonox (Nitrous oxide and oxygen) is a colourless, odourless gas made up of half oxygen and half nitrous oxide. It's also known as laughing gas. It can take the edge off labour pain, rather than blocking it out