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
IV ultrashort acting barbiturate: 
Select and explain. 
A. Meprobamate, B. Pentobarbitone, C. Thiopentone, D. Phenobarbitone
C: Thiopentone
Answer: C: Thiopentone 
Explanation: None