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: Biochemistry
A child to emergency with accidental ingestion of cyanide. It blocks citric acid cycle by blocking: 
Select and explain. 
A. Aconitase, B. Acetyl-CoA production, C. NAO, D. Citrate
C: NAO
Answer: C: NAO 
Explanation: Ans: C. NAORef: Harper 30Ie p132)Cyanide blocks citric acid cycle by blocking NAD+