This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Which of the following vitamin deficiency causes Wernicke Korsakoff syndrome? 
Select and explain. 
A. Thiamin, B. Riboflavin, C. Niacin, D. Cobalamin
A: Thiamin
Answer: A: Thiamin 
Explanation: Vitamin Functions Deficiency Disease B1 Coenzyme in pyruvate and a-ketoglutarate dehydrogenases, and transketolase Regulates Cl- channel in nerve conduction Peripheral nerve damage (beriberi) or central nervous system lesions (Wernicke Korsakoff syndrome) Reference: Harper; 30th edition; Page no: 550