This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
'Second gas effect' is exeed by which of the following gas when coadministered with halothane: 
Select and explain. 
A. Nitrous oxide, B. Cyclopropane, C. Nitrogen, D. Helium
A: Nitrous oxide
Answer: A: Nitrous oxide 
Explanation: (Ref: KDT 6/e p369) Concentration effect, second gas effect and diffusion hypoxia are seen with inhalational agents used in high concentrations (like N2O).