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
Which of the following deficiency in alcoholics inhibit pyruvate dehydrogenase? 
Select and explain. 
A. Thiamin, B. Niacin, C. Riboflavin, D. Ascorbic acid
A: Thiamin
Answer: A: Thiamin 
Explanation: Arsenite and mercuric ions react with the - SH groups of lipoic acid and inhibit pyruvate dehydrogenase, as does a dietary deficiency of thiamin, allowing pyruvate to accumulate. Many alcoholics are thiamin-deficient (both because of a poor diet and also because alcohol inhibits thiamin absorption), and may develop potentially fatal pyruvic and lactic acidosis. Ref: Harper 28th edition, Chapter 17.