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: Dental
N2O more than 30 — 40% causes 
Select and explain. 
A. Diffusion hypoxia, B. Anoxia, C. Amnesia, D. Ataxia
C: Amnesia
Answer: C: Amnesia 
Explanation: None