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
Which one of the following is the fastest acting inhalational agent: 
Select and explain. 
A. Halothane, B. Isoflurane, C. Ether, D. Sevoflurane
D: Sevoflurane
Answer: D: Sevoflurane 
Explanation: Sevoflurane