This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
Wernicke's encephalopathy is due to the deficiency of: 
Select and explain. 
A. Niacin, B. Cyanocobalamine, C. Pantothenic acid, D. Thiamine
D: Thiamine
Answer: D: Thiamine 
Explanation: D Harper, 26th ed. p. 489 & 25th ed, p. 628