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
The reaction inhibited in thiamine deficiency is 
Select and explain. 
A. Pyruvate to acetyl CoA, B. Citrate to alpha ketoglutarate, C. Succinyl CoA to fumarate, D. None
A: Pyruvate to acetyl CoA
Answer: A: Pyruvate to acetyl CoA 
Explanation: PDH requires thiamine as a cofactor to convert pyruvate into acetyl CoA.